G92 GTS if you want one card, but for $300 you could get two 9600GTs. I see you have an SLI board.. You know you want to.
I'd go with the 8800gt if you want something absolutely under 200$, but if you can find an 8800gts on sale/MIR that'll dump it under 200$ grab that for sure, the dual slot cooling is very nice. I've heard to avoid MSI video cards...I guess their capacitors are lower quality? I have experience, just what I've heard. All I know is I love eVGA and buy from them almost exclusively....so if you can find an eVGA or XFX 8800gts under 200$ buy buy buy buy buy it.