You guys can't be serious.. You are recommending XP over W7 to a media editor and gamer? You can't use more than about 2 GB RAM (depending on your video card) on a 32-bit machine and directx 10 or 11 won't work. Sure, there are a few compability issues (haven't seen any after 2 years myself though), but W7 even has a "XP-mode" meant for just this purpose that will fix that right away.
To everyone saying "why reinvent the wheel" etc. etc., you might as well recommend him this cellphone:
or this car:
A 64-bit OS is an absolute must if you want a modern and future proof machine. I would even gladly pick Vista 64-bit over XP.