Cool list of software. The only stuff I pay for is games. Coincidentally, the only thing I use Windows for is games.
Everything else I use I use in linux, and is free open-sourced software:
Mozilla for Browsing/Email/News/Download Management
Gaim for IMing. Using plugins, support for all the popular IMs is available.
KVirc for IRCing (supports multiple simultaneous server connections).
Vim for HTML/PHP/ASP/Perl/C/C++ development. *Snicker*
Eclipse for Java development.
OpenOffice for word processing, spreadsheets, etc..
Gimp for image editing
XMMS for Audio playing (MP3s and CDs).
Audacity for editing Audio.
Xine for playing DVDs and watching video.
Xawtv for TV Tuning (I have an ATI TV-Wonder and a 19" monitor, no need for a TV).
X-CD-Roast for CD burning. It can also create ISOs from a cd or from files on a filesystem.
KDE's Ark for working with archives in a gui (I rarely do).
Oh, and I play
Neverwinter Nights in Linux.
At the moment, I only use windows for 3 games:
PlanetSide - Windows only
Tactical Ops: Assault on Terror - There is a linux version, but there isn't support for my Nostromo n50 Speedpad, and I play this more often than any of the other FPSes I have with the possible exception of planetside, now that I've found it. I've got a wireless keyboard and don't wanna kill the batteries all the time.
Magic The Gathering Online - Windows only.
I also have Warcraft III, which I like, but don't play anywhere near as much as the other games.