Kind help reqd. : Double Agent problem

Guys, I just got a new pc...not very high end, a mediocre one:

Here are the specs:
Core 2 Duo 2.2ghz
2gb ram
200 SATA gb hdd
XFXNvidia GeForce 8500gt 512mb pciexpress 500Mhz
Sony DVDRW
WinXP SP2

Along with it, I also bought SplinterCell:Double Agent.
Thing is,
The game installed with no problems,
But when i'm running the game, the graphics are coming all crappy.
Only Sam's goggles can be seen, the environment is hodgepodge..
The game ain't PLAYABLE.
Can anyone help me out?

Any help would be appreciated.
Thanks.