Yeah ofcourse you can , I suggest using Icehancer:
(sort on most downloaded)
You can try out any version you like, just backup your entire game so you don't have to reinstall every time.
I'd be cautious with trafficload though, in combination with alot of HD cars it can slow your game down alot. I have basicly the same setup as you (only difference is 4GB RAM and 6900 series AMD Radeon) and trafficload made all my buildings disappear (in the distance).
You can try using traffic control system or other taxi bugs, or you could just give trafficload a go.. you should experiment to see which one works for you. I've tried out a few carpacks and anti-taxi bugs but I like how smooth the game plays with default cars and no taxibug fixes so I've removed all my custom cars from the game.