You can buy a lot for 2000 bucks. Obviously get an Athlon XP, what speed is up to you. For a video card, I'd say either go with the Geforce 4 Ti4600 or Radeon 8500... but if you have 2000 bucks, might as well splurge on a All-in-Wonder Radeon 8500DV.
With 2000 bucks you can afford an Asus board 😛
Ah really, I don't know... what are you planning on using your system for? Gaming, multimedia, etc...? need more info