My computer is too good?

[irregular]

Hey guys I just got a new computer recently:
2.73 gigahertz AMD Athlon 64 X2 Dual Core
NVIDIA GeForce 9600 GT
2 GB memory DDR


Anyway first thing I do is install DW

I try to play different missions, but the game always lags out on me. Some people say I need to download something to make my graphics card worse for a while when I play.
Anyone finding themselves having to do this?

Thanks