How fast does a AMD AthlonXP 2800 work? Would that be enough to play Farcry, some other games, and the basic Microsoft programs?
Yes, it'd be fine. However, for that you'd want to make sure you have a solid video card. You want to look at a Radeon 9800 Pro, and they run around $200 on-line. Yes...the CPU is important, but the newer FPS titles demand a hearty graphics card to run them.
so would it work just fine to the point where i definately wouldn't need anything better or do mean something else when you say it would be fine?
Is it the best CPU you can get? No. But unless you're rolling in money, it's perfectly acceptable. I run an Athlon XP2400+ in my main box, and D00M 3 and FarCry run fine on it, although I'd get better frame rates if I updated my video card. The CPU is important, but not the be all, end all. For FPS gaming, you want to make sure to invest some good money in a video card. You can get away with a not-so-blazing CPU (although you don't want to go with the slowest one you can get, as D00M 3 eats slower CPUs alive), but you will regret it if you want an enjoyable gaming experience.