I am looking to upgrade but I don't know which PCI-E video card to get. I want one that gives good performance for the price, and I am not looking to spend more than $300usd (cheaper is better). I want to be able to play newer games including Oblivion, FEAR, etc. on 1280x1024 using high or mid-to-high graphics levels, but I also think my CPU may be somewhat of a bottleneck (nothing else in my system will be). Right now I have an Intel Pentium 4 640 at the stock speed of 3.2GHz. I will not be able to upgrade for a while, so if it's going to limit the video card I can use, so be it. The three cards I've been looking at are the eVGA 7600GT, 7900GT KO, or the Sapphire x1800XT. Which of these three should I go for, or is there something else that's a better deal? I appreciate any help I can get.

7900 GT or X1800 XT are the best two in the price range.

Oblivion will run better on the X1800XT. But you can't go wrong with either 7900GT or X1800XT.