GTA IV - Low FPS on Windows 7 RC 64-bit

So, I'm running Windows 7 Build 7100 64-bit with a Mac Pro (no haters please). Main specs are:

1x Intel Quad-Core Xeon @ 2.8GHz
2GB 800MHz DDR2 RAM
EVGA Nvidia GTX 285 1GB (Mac-Edition)

I have been playing many many games with these specs, and they all run extremely well... except one. GTA IV runs horribly. The game starts up okay, but it runs super slow. I'd say (from memory) around 10FPS minimum, 25 max. It's pretty much unplayable. I've tried a variety of different drivers, Nvidia 181, 185 and 186 I believe, but it still won't work. I've heard it runs well on v180, but those are Vista only, right? I have played it before on 1920x1200 (med) with Windows XP SP3 and an NVIDIA 8800GT 512mb.

Anyway, any help would be nice. I'm new to this forum, so if I made any thread related mistakes, sorry.

Thanks.

I have 6600 intel dual core 2.4 x2, 8800GTS, 2gigs ram, win 7 64bit and 11 - 22 fps in game is best i get.

I opened up resource manager and see that it's all processor related, and after doing research it seems this is due to bad coding on rockstar's part. It's not your machine if you have decent proc', mem and vid card.

No fix available and all patches installed.. Put it at 800x600 lowest settings, still had low FPS.

Find another game maker for your PC. Rockstar apparently ripped us off.

The thing that gave me a few more fps was lowering the distance draw. That is the most CPU intensive thing. Also, most everything on medium, resolutions makes no difference.