Help me choose my next gpu under 300usd!

[karekano]

Hello, I've decided to look for a new video card for preferably under 300 usdollars.
Here is my system specs currently or would i be better off getting another of what i have and just sli'ing them?
pc power &cooling 750 watt ps
BFG nvidia geforce 8800 GTS OC 320mb gddr3
windows xp service pack 2 (have huge errors whenver i try and get 3 so not running 64 bit sigh)
amd phenom 9500 quad core
4gb of corsair shows at 3.25gb of ram
asus M3A board bios 1104
mainly like to run world of warcraft and other games just wondering what i can do to help it out
also running a LG 23" W61 lcd monitor
thanks so much in advance!

 

[roush2fast]

^+1 on the GTX260 core 216. It's an incredibly powerful card for the price. You can get one right now for $150 after rebate at the egg.