graphics card upgrade

[beanie414]

hi im looking to upgrade my Nvidia Geforce 8800GTX 768MB PCIe Graphics card and seeking advice on what to get i have £150-£200 to spend i will be using it for gaming and i will probably use 32" tv at times for watching films etc heres some system specs,what would fit into this motherboard im not computer savvy enough to change that,would i need to change anything like my power etc any advice is appreciated ty in advance

windows 7
Intel Core 2 Q6600 2.4GHz Quad Core
Asus P5Q Motherboard LGA775
6 GBMemory
Nvidia Geforce 8800GTX 768MB PCIe Graphics
Corsair 620watt Modular PSU
Coolermaster Mystique 631 silver Aluminium Case
24" monitor

 

[beanie414]

hi and thanks for reply i was looking at that card earlier just wasnt sure if my computer could run it ok,i havent over clocked anything before so not too sure i want to try it atm in case i make a mistake is my comp still ok to run it withought oc,also some one i know suggested radeon 6870 1GB GDDR5 i know thats cheaper wasnt sure of the diff though im not really clued up on graphics cards ty