@ poc: Can you post a DXdiag and we'll go from there?
I have a similar setup as yours and it runs fine for me.

ASUS M3N72-D
AMD Athlon 64 X2 5600+ Brisbane @ 3GHz
4 Gigs DDR2 PC6400 Dual Ch. Corsair
ASUS GeForce 9800GT 512MB x2 SLI
Win7 64bit or XP Pro x64