8800 gts running slow in lostplanet

[Eddie3dfx]

Well I have a xfx 8800gts that runs at 650/975 watercooled.
System is an x3210 oc'd to 3.5 watercooled. 2gigs of ballistix 1066, 680i, etc.
Xp pro, direct x9, latest drivers and bios, etc.
1280x960 and highest setting for everything, except I believe shadows, since only directx10 lets you put it on high.
I'm only getting 22-30fps .. avg around 24fps I believe. also, my vsynch and aspect correction are off
I assumed this was normal, but on this website, it shows the gts averaging 37.1 .. and I'm sure these are based on stock clock speeds as well.
Also, their benchmarks are directx10 under vista, which is 10-20% slower than xp with the same settings...
Why am I getting a lower frame rate?

http://www.firingsquad.com/hardware/lost_planet_demo_directx_10_performance/page7.asp

[dnottis]

320 or 640?

[mad_skills]

if you have a 320Mb model then it should be ok, 'cause 320 could only make trouble because the lack of ram in resolutions above 16x12, otherwise fps shouldn't be much different than the 640Mb model