Sound advice from Neatton and Xanoth (Except the Silky Venom link of course!
)
If you cant resist the instant gratification urge though and want to proceed with a PC right now your best bet would be a AMD x2 socket 939 chip of your choice, a Nvidia nForce 4 motherboard from your favorite manufacturer (For example Abit, Asus, MSI), at least a gig of RAM from a well known memory manufacturer like (Corsair, Crucial or OCZ) and a nice ATI 1800 or Nvidia 7900. If you take a look at some of the rigs in the Gaming Rigs section at the top of this forum you can get some more precise item descriptions. If you have any questions about why those people chose those components Im sure a quick post in their thread would get you a helpful answer.