Safdar Mirza

7-Zip - Zip files.

Filezilla - FTP server/Client.

VLC - Video Player.

Thunderbird with Lightning Calendar extension - Email client. works with google mail. Gmail.

Pidgin - Chat software ..

InfraRecorder - CDROM/DVD ROM burning software - Free.

Nero Burning ROM - Alternate of InfraRecorder. CDROM/DVD burning software. May cost.

The GIMP - Just like photoshop but free.

VirtualDub - Video Editor.

Miro - Video Juke Box.

Open Office - Just like MS office but free.

LibreOffice - Alternate of Open Office.

Iron - German web browser, just like chrome.

Audacity - the single best open source audio edito

RSSOwl - must-have RSS reader

Notepad ++ - reliable notepad application

ClamAV - Malware detection

AVG anti-virus - Anti Virus

Clonezilla - OS backup - Snapshot of the harddrive with ISO image.

Norton Ghost - Another tool to do the hardrive snapshot.

Ekiga - Video Conference ..

Camstudio - Desktop capture

Dia - Creating diagrams. flowchart.

Microsoft Visio - Alternat to Dia.

Wikidpad - Data sorting and cross linking.

Source: http://itmanagement.earthweb.com/osrc/article.php/12068_3907631_3/Top-20-Open-Source-Apps-for-Windows.htm