Open Source Alternative to Commercial Software - System Utilities

Acronis Partition Expert
GParted is the Gnome Partition Editor application. Before attempting to use it, here is some basic background information. A hard disk is usually subdivided into one or more partitions. These partitions are normally not re-sizable (making one larger and the adjacent one smaller) The purpose of GParted is to allow the individual to take a hard disk and change the partition organization therein, while preserving the partition contents. GParted is an industrial-strength package for creating, destroying, resizing, moving, checking and copying partitions, and the filesystems on them. This is useful for creating space for new operating systems, reorganizing disk usage, copying data residing on hard disks and mirroring one partition with another (disk imaging).

Adobe Acrobat Reader

Xpdf is an open source viewer for Portable Document Format (PDF) files. (These are also sometimes also called 'Acrobat' files, from the name of Adobe's PDF software.) The Xpdf project also includes a PDF text extractor, PDF-to-PostScript converter, and various other utilities. Xpdf runs under the X Window System on UNIX, VMS, and OS/2. The non-X components (pdftops, pdftotext, etc.) also run on Win32 systems and should run on pretty much any system with a decent C++ compiler. Xpdf is designed to be small and efficient. It can use Type 1, TrueType, or standard X fonts. Xpdf should work on pretty much any system which runs X11 and has Unix-like (POSIX) libraries.
Foxit Reader Foxit Reader is a free PDF document viewer and printer, with incredible small size (only 2.1 M download size), breezing-fast launch speed and amazingly rich feature set. Foxit Reader supports Windows 98/Me/2000/XP/2003/Vista. Its core function is compatible with PDF Standard 1.7.
Sumatra PDF is a slim, free, open-source PDF viewer for Windows. Sumatra has a minimalistic design. Simplicity has a higher priority than a lot of features. It's small and starts up very fast. It's designed for portable use: it's just one file with no external dependencies so you can easily run it from external USB drive.
Ghostscript is an interpreter for the PostScript language and for PDF, and related software and documentation.

Camtasia Studio and Macromedia Captivate
xvidcap is a small tool to capture things going on on an X-Windows display to either individual frames or an MPEG video. On Windows machines there are commercial tools like Lotus ScreenCam or Camtasia which do a very good job esp. for the purpose I was needing such a tool for: Software documentation, esp. installation procedures and such.
CamStudio is able to record all screen and audio activity on your computer and create industry-standard AVI video files and using its built-in SWF Producer can turn those AVIs into lean, mean, bandwidth-friendly Streaming Flash videos (SWFs)

Google Desktop Search
DocFetcher is a desktop search application: It allows you to quickly access documents on your computer by typing keywords. - You can think of it as Google for your local document repository. The application is currently available for Windows and GTK-based Linux distributions.

Hummingbird Exceed

Xming is the leading free unlimited X Window server for Microsoft Windows (XP/2003/Vista). Xming is fully featured, light and fast, simple to install and because it is standalone native Microsoft Windows, easily transported portable as a Pocket PC X server. It is totally secure when used with SSH and optionally includes an enhanced PuTTY Link SSH client and a portable PuTTY replacement package.

Macrovision InstallShield
Inno Setup is a free installer for Windows programs. First introduced in 1997, Inno Setup today rivals and even surpasses many commercial installers in feature set and stability. It supports all versions of Windows in use today: Vista, XP, 2003, 2000, Me, 98, 95, and NT 4.0. (No service packs are required.)
InstallJammer is a multiplatform GUI installer designed to be completely cross-platform and function on Windows and most all versions of UNIX with eventual support for Mac OS X. It features a very powerful install builder with support for multiple themes and a high level of configurability for installers. Installers are built as single executable files for easy distribution over the web and handle installing everything you need for your application in a simple, cross-platform way.
Launch4j is a cross-platform tool for wrapping Java applications distributed as jars in lightweight Windows native executables. The executable can be configured to search for a certain JRE version or use a bundled one, and it's possible to set runtime options, like the initial/max heap size. The wrapper also provides better user experience through an application icon, a native pre-JRE splash screen, a custom process name, and a Java download page in case the appropriate JRE cannot be found.
NSIS (Nullsoft Scriptable Install System) is a professional open source system to create Windows installers. It is designed to be as small and flexible as possible and is therefore very suitable for internet distribution. NSIS is script-based and allows you to create the logic to handle even the most complex installation tasks. Many plug-ins and scripts are already available: you can create web installers, communicate with Windows and other software components, install or update shared components and more.

Nero Burning Rom and Roxio RecordNow
K3b is the CD/DVD creator for Linux - optimized for KDE - licensed under the GPL.
InfraRecorder is a free CD/DVD burning solution for Microsoft Windows. It offers a wide range of powerful features; all through an easy to use application interface and Windows Explorer integration.
Burn is a burning application for Mac OS X
Cdrdao records audio or data CD-Rs in disk-at-once (DAO) mode based on a textual description of the CD contents.

StarNet X-Win32 version
Xming is the leading free unlimited X Window server for Microsoft Windows (XP/2003/Vista).

Symantec Norton Ghost
Partimage is a Linux utility which saves partitions having a supported filesystem to an image file. Most Linux and Windows filesystems are supported. The image file can be compressed with the gzip / bzip2 programs to save disk space, and they can be splitted into multiple files to be copied on CDs / DVDs. Partitions can also be saved across the network since version 0.6.0 using the partimage network support, or using Samba / NFS. If you don't want to install Partimage, you can download and burn SystemRescueCd. It's a livecd that allows to use Partimage immediately even if your computer has no operating system installed (useful to restore an image), and it allows to save an image on a DVD on the fly.
g4u ("ghosting for unix") is a NetBSD-based bootfloppy/CD-ROM that allows easy cloning of PC harddisks to deploy a common setup on a number of PCs using FTP. The floppy/CD offers two functions. The first is to upload the compressed image of a local harddisk to a FTP server, the other is to restore that image via FTP, uncompress it and write it back to disk. Network configuration is fetched via DHCP. As the harddisk is processed as an image, any filesystem and operating system can be deployed using g4u. Easy cloning of local disks as well as partitions is also supported.

Symantec Veritas NetBackup

Bacula is a set of computer programs that permit you (or the system administrator) to manage backup, recovery, and verification of computer data across a network of computers of different kinds. Bacula is relatively easy to use and efficient, while offering many advanced storage management features that make it easy to find and recover lost or damaged files.
AMANDA, the Advanced Maryland Automatic Network Disk Archiver, is a backup system that allows the administrator to set up a single master backup server to back up multiple hosts over network to tape drives/changers or disks or optical media. Amanda uses native dump and/or GNU tar facilities and can back up a large number of workstations running multiple versions of Unix. Amanda uses Samba or Cygwin to back up Microsoft Windows desktops and servers.
StorageIM is an open source monitoring and reporting tool for storage systems and storage networks built around the CIM/SMI-S industry standards and is designed for use as a development aid within the IT vendor community. StorageIM is the first storage configuration and resource monitoring tool in the industry to be built with these rapidly emerging standards as its core. As a result StorageIM supports HBAs, Arrays, Switches, and Tape Libraries across vendor’s products with a high degree of interoperability and reliability. StorageIM uses the highly scalable xIM architecture as its core and thus, can be rapidly expanded with new capabilities.

UltraEdit-32
Notepad++ is a free source code editor (and Notepad replacement), which supports several programming languages, running under the MS Windows environment. This project, based on the Scintilla edit component (a very powerful editor component), written in C++ with pure win32 api and STL (that ensures the higher execution speed and smaller size of the program), is under the GPL Licence.
SciTEis a SCIntilla based Text Editor. Originally built to demonstrate Scintilla, it has grown to be a generally useful editor with facilities for building and running programs. It is best used for jobs with simple configurations - I use it for building test and demonstration programs as well as SciTE and Scintilla, themselves. SciTE is currently available for Intel Win32 and Linux compatible operating systems with GTK+. It has been run on Windows 95, NT 4.0, Windows 2000, and on Red Hat Linux 8 and 9 with GTK+ 1.2 and 2.0.
jEdit is a text editor with hundreds (counting the time developing plugins) of person-years of development behind it. To download, install, and set up jEdit as quickly and painlessly as possible, go to the Quick Start page. While jEdit beats many expensive development tools for features and ease of use, it is released as free software with full source code, provided under the terms of the GPL 2.0.

VMware Server ESX

VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers, it is also the only professional solution that is freely available as Open Source Software under the terms of the GNU General Public License (GPL). VirtualBox runs on Windows, Linux and Macintosh hosts and supports a large number of guest operating systems including but not limited to Windows (NT 4.0, 2000, XP, Server 2003, Vista), DOS/Windows 3.x, Linux (2.4 and 2.6), and OpenBSD.
Cooperative Linux is the first working free and open source method for optimally running Linux on Microsoft Windows natively. More generally, Cooperative Linux (short-named coLinux) is a port of the Linux kernel that allows it to run cooperatively alongside another operating system on a single machine. For instance, it allows one to freely run Linux on Windows 2000/XP, without using a commercial PC virtualization software such as VMware, in a way which is much more optimal than using any general purpose PC virtualization software.
OpenVZ is an Operating System-level server virtualization solution, built on Linux. OpenVZ creates isolated, secure virtual environments — VEs (otherwise known as virtual private servers, or VPSs) on a single physical server enabling better server utilization and ensuring that applications do not conflict. Each VE performs and executes exactly like a stand-alone server; VEs can be rebooted independently and have root access, users, IP addresses, memory, processes, files, applications, system libraries and configuration files.

WinRAR and WinZip
7-Zip is open source software. Most of the source code is under the GNU LGPL license. The AES code is under a BSD LICENSE. The unRAR code is under a mixed license: GNU LGPL + unRAR restrictions.