Building a gaming computer, need help

[Lambodrifter]

So on Christmas day my dad told me that we were going to build a gaming computer. It is a great gift, but he is not very motivated and doesnt really want to do anything. He already has the case and motherboard on order, but he spent all day yesterday trying to figure what graphics card to get and he didnt make a decision. I know if I dont step in and take inititive it will NEVER get done. I know a fair amount about computers, but I've never built one before.

I already know I want 2 gigs of RAM and a decent size HDD, but I need a little help the the GPU and CPU. The problem is, my dad bought a workstation motherboard. It has an LGA771 processor slot, so most Core 2 Duos wont fit it seems. So I need to know the best Xeon processor for gaming. As for the GPU, i just dont really know which one to get. I want one that will be able to run modern games at high settings (excluding Crysis) but is under $300. I will be playing COD4, Test Drive Unlimited, and Rainbow Six Vegas, to name a few.
Thanks in Advance!

[*Stan*]

Hi

strange every mist this question!

COD 4 recomends NVDIA Geforce 6600 or ATI Radeon 9800Pro or better, and I am sure that they will play rainbow six if you get 256mb I had the game someware but cant find the case for what it asks for in hardware.

COD needs pixal shading, allot of people that could play COD 2 think that they will be able to play COD 4 but they are not being able to, as with COD 2 you could get away with not having pixal shading.

I say this to alot of people, you really dont need 2 core CPU's for gaming, what CPU socket is your motherboard?