The minimum spec:

3,2 GHz Single Core; 1 GB (1.5 if Vista run) RAM; 128MB SM3 Video Card (From 6600GT/X1600); 5.5GB Free Space

But you didn't mention about the RAM and CPU, we know that you have a Geforce 8800; but if you earn 12xxx pts on 3DMARK06, I think you can run smoothly on medium quality