You probably won't find a computer with XP, more than likely Windows 7 will be what's available (not including Macs). Don't get Vista unless it's a phenominal computer deal and has it preloaded. Even then I'd upgrade it to Windows 7.
Most big software products will run, and of course Matrix (not Talonsoft). The lesser known add-ons and freebies we tend to collect over time may or may not. Hard to say.
There's a compatibility tester for Windows 7 (see link below). It's to test whether your computer can handle an upgrade, but I believe it will tell you whether the programs that you have currently will run without needing to upgrade/replace them:
http://www.microsoft.com/downloads/en/de...97c146af15
Hope that helps.
Dave
Resolve then, that on this very ground, with small flags waving and tinny blasts on tiny trumpets, we shall meet the enemy, and not only may he be ours, he may be us. --Walt Kelly