Graphics card upgrade help

2 months ago, I built this new rig and I wasn't happy with it at all when I first ran it. Of course, after OCing the 8600GT to 690/480 and the Q6600 to 333 x 9 (ClockGen) it was loads better. But even now running Crysis all Low [1280 x 800] no AA, I get an average 30 fps.
I didn't get the 8800GT 512 as it was twice as costly as the 8600GT [i don't live in the US] and the 9800GX2 was thrice as costly. But since I am not happy, I am considering either the 8800GT 512 ot the 9800GX2. Is it worth the upgrade? Both these cards seem real costly.... In case I do upgrade, I want to run future games in High graphics for at least 2 more years.