4GB DDR3 RAM
Oh and is it a fact that games run better on win xp than win 7?
Check that your drivers are up to date. You can also try turning PhysX off completely.
And no, it is not a fact that games run better in XP. It depends on a great many factors. Some games work better in 7 than in XP while others don't work at all. Benchmarks suggest that XP may be a little faster, but not enough to be noticed in most cases.