Well I think I can help you!!!
You're using Vista and you only have 2gb of RAM!
VISTA IS YOUR HOG! It takes 2GB to fire the sucker up...so by my guess you're lucky you're even getting the game to work (say good night to Crysis,Empire: TW, etc..).
I would suggest adding a few more 2gb sticks in...personnaly I have a Intel Quad Core @ (2.66ghz), Vista SP1, 6GB RAM, Gefore 9500GS (9800 on its way
), Direct X 10
And I'm sure its those RAMs...
I have the RAM monitering Vista device...and am writing this with NO OTHER PROGRAMS ON! Yet it states that 45% of my RAM is being used (45% of 6GB is a fair amount for a single OS).
So yeah my reply stands...add in a few GBs of RAM if you can!