It's kind of BS to say it *requires* a quad core. I'm running a Core 2 duo E8500 @ stock 3.1 with a GTX 460 and I'm getting around an average of ~40. That's with most things on high except shadows and night shadows which are just on normal. Draw distances are left at auto-configured levels.
You can't crank it all the way up without a powerhouse pc, but it's can be made to look better than the xbox and still be playable on most machines, at least if you have a video card with 1gb of ram.
Rockstar social club + GFWL... if you can handle those two things without emo-rage-quiting then you will have a good game..
GFW made me regret buying Batman:AA and RFG...
I can't play em on my laptop...Which i use from when i'm not home or traveling.
I've never encountered a problem with GFWL. Don't understand what all the complaints are about.