this is a much better card and hardly more expensive. http://www.newegg.com/Product/Product.aspx?Item=N82E16814161235
also this will run better on the pci-e 1.0 x16 slot that you have. i've heard of a lot of 8800s not working at all on pci-e 1.0 and a bunch of associated problems that aren't easy to fix.
i just bought one and played crysis on very high settings and it was playable. i was amazed. i do have a better processor than you (AMD 5600+ X2 ~2.9 GHz) but you should see an amazing
improvement with this card. the 8800GT isn't bad either, though.