That's strange...I know we have the same setup and High is very very playable for me @ 1440 x 900. In fact Very High is almost playable at around 20 FPS. I did OC my E6600 to 2.9 GHz, and that seemed to help a bit.
then i guess i need to shop trying to discuss whats playable and not because it seems even the definition of playable is so varied. for me, 20 fps is not even close to being playable. different peoples sensitvity to frame rate is different. for me the very second it goes below 40 fps and can "feel" it, there is a sudden slowness. and im talking about fast paced FPS.
but its all good though, now that i somewhat understand how G80/G92 works, in my opinion the next high end from nvidia will be nothing short of a monster and maybe then ill buy crysis. right now TF2 is all i need.