i suggest you upgrade your card - the 6600 is pretty damn old for todays' standards (granted, it did have a very long life time).
if u just want great DX9 performance, get a 7800-7950. or an XFX 7600GT (it performs like a 7800 cuz its factory OC'd and souped up).
i'd recommend XFX cards cuz theyre damn fast and quite cheap.
go to Newegg, narrow it down to DX9 AGP cards, sort by best rating
, and you'll see my 7600GT comes in first
you have a good processor tho, much better than my ghetto 3GHz P4 (HT)