Meh, I've pretty much given up on Crysis, but I thought maybe someone could shed some light on this.  I get around 12,500 in 3dmark, and every other game I can max out easily.  I've read a ton of people running at higher resolutions with an 8800gt or gts(which is what, 10% faster?) with decent frame rates at 1280x1024 or 1440x900.  I'm running the demo and with everything high, no aa at 1440x900 its unplayable.  can i safely assume the retail version of game with updates fixes this and thats why my performance is crap or is the retail worse? btw... 2gb crucial ballistix 800, p35-ds3l, evga 8800gt @ 720/999, e8400 @ 3.6ghz, vista 32bit.

What Display drivers are you running?  There have been two patches for the retail game and many driver releases that are aimed at Crysis single or multi GPU performance. If everything is in order, the demo should be playable at 14x9 high.  The games gets way more demanding later on past the demo mission.  The cutscenes should be your worst fps in the demo.  And Vista may not be helping so I'd make sure your forcewares are up to date.

I have the latest vista 32bit drivers from guru3d.com.  I've tried running the game under dx9 in vista.  noticeable improvement at lower resolutions, but higher than 1024x768 is still not playable.

Try viewing your framerates with the console or fraps.  What is your range of fps?  Your explanation of how it's playing sounds like the 256MB GT not the 512MB GT like you have. (huge difference in this game)  
 
I run Guru 3D 17x.xx drivers myself, but Have you tried a 169.xx official drivers too?

No single card can play Crysis well at the minute, with the exception of the GX2...  
 
I had a similar setup last december to yours... and I completed the game at 1280 x 720 resolution at HIGH settings using Windows XP. 30FPS or thereabouts.

^ But if the demo is unplayable, imagine the last half of the retail game.  

yeah once the snow appears, wave goodbye to a double figure framerate lol

Id say the demo version runs a fair bit worse than the full game.  The full game has been patched twice, which should help matters plus drivers from both Nvidia and ATI are tuned to the full version, which is a later build than the demo version.  Your gt should stomp through the full game, my 2900 pro(STOCK) gets 30fps average in the first half of the game in XP @1400x900 with all on high, with shadows, particles, game effects, volumetric and post processing on medium.  Your gt should beat that by a long ways.  Try the full thing, fully patched with the new forceware 174, with shadows and post processing on medium.  You'll lose like 5% image quality for a substantial gain in fps.