This is a list I made for Windows users to use instead of using the bloated propriety rubbish.
Internet Explorer - Firefox
Microsoft Outlook - Spicebird or Thunderbird
iTunes - Songbird (0.4 is pretty stable now, just some little bugs)
Windows Media player - VLC or Miro
Nero - Infrarecorder (http://en.wikipedia.org/wiki/InfraRecorder) Wish it was available for Linux, its 10 times better than brasero, K3B or Nero. ITS AN AMAZING APP I'VE DISCOVERED RECENTLY. The website is poor but the app is AMAZING!!!
MS Office - OpenOffice
Windows Movie maker - Pinnacle VideoSpin (Not GPL, but its free - http://videospin.com/ )
Photoshop - GIMP
MSN Messenger - Pidgin
Inspiration - VYM or Freemind
Bittorrent - Deluge
Photo Organizer - Picasa (Not GPL, but its free)
Adobe Illustrator - Inkscape or Xara Extreme
Adobe Indesign - Scribus
Anti-virus (Commercial) - ClamAV is very poor from what I've heard. I strongly recommend NOD32
Anti-virus (Freeware) - Avast & AVG
So all you have to spend on software is Windows XP and the anti-virus.
Add to the list if you want