1. 9700 Pro won't cut it for Doom 3, max details with full DX 9.0
You get 60 fps in 800x600... unless they make some severe changes from the alpha. You're fine for UT2k3 though. You're gonna need at least GeForce FX or whatever ATI pulls out next for Doom 3, which is fine cause it won't be out for another year anyway.

If you want affordable and useful proc right now, about the 2000+ to 2200+ range is right before the prices get up there. That will tide you over until next year when you can get a real upgrade with the new video card (if you REALLY want that detail on Doom 3). But by then you'll also need a new mobo, not to mention new memory that can handle the timings need for DDR400. That's only if you want to keep ahead of the game... I'm still using a 1 Ghz Athlon, which works fine for everything cept UT2k3 *cries*