yea it will the 9800 gx2 is Two 8800gt in one card
you will see alot better performance in games and if i where you i would buy a second one before they run out to have quad sli
A GX2 is a good upgrade option for low end 8000 series cards and earlier, but because of 512MB RAM and crap drivers, the card is simply too limiting as a full-time replacement; its more of a holdover card while you wait for something more powerful in your price range. Still, it can still chug out >30 FPS with most anything, so its not all bad.
The issue is, that SLI scaling on the card is bad enough, Quad SLI + Buggy drivers = wouldn't even try it myself.