Newegg does sell NVidia cards, I've bought two from them. Your case is a mid-tower, typical desktop size. An ATX full-tower case will allow for the largest components, such as the newer graphics cards, but is often more expensive and heavier. If you go with 4 GB or more of RAM, you will need a 64-bit OS to use all of it. Windows XP 64-bit is not that great, it has compatibility issues. Vista 64-bit is much better at 64-bit than XP. Graphics cards can be cheap to insanely expensive, especially if you decide to SLI or Crossfire the cards. Your motherboard will determine if you get to use SLI or Crossfire. The CPU selected has a great value, stick with it. I suggest getting the ASUS RAMPAGE FORMULA
motherboard, keeping the same CPU, and a DIAMOND 4870PE5512OC Radeon HD 4870
(Or, if you have lots of money the DIAMOND 4870X2PE52G Radeon HD 4870 X2
). The motherboard I chose allows for up to 8 GB of RAM, consider getting as much as you can. Next, you need a PSU to power the thing. The CORSAIR CMPSU-750TX 750W
comes highly recommended.