Ok OP, you got lucky, I have the exact same MBP, with the 8600gt, (although I have 4 gigs of RAM) and after being a long time lurker I decided to sign up to tell you about gaming with my MBP.
First of all, make sure you've got Windows 7 installed via bootcamp because games will just run faster on that side.
I have played through the open BWE Diablo III had a few weekends ago, and the game runs okay, not ideal, but I'd say on medium to low with decent FPS.
If it is of interest of you, I also played the GW2 BWE and the game ran a little less than ideal but still playable on low.
Other games I have had installed on here have been Dragon Age (first one), and everything from Valve (HL Series, Portal Series, TF, CS) all of which work pretty well.
In all honesty she's not the fastest ship, as a matter of fact I will be upgrading mine to a current model MBP or the new one if Apple if it comes out soon. That being said she still has a lot of game in her, and a lot of games these days will still run alright, which is why I will be passing her on to my girlfriend, who is slowly learning to get her game on.
If I had to suggest any upgrades, upgrade your 2 gigs to 4 gigs of ram, maybe throw in a solid state drive if you have money to throw around, and make sure your drivers are all up to date on the windows side. Also tinker with the video settings in the game and see what works, I usually have no idea what I am doing but I seem to find a decent setting after a little trial and error.
Hope it helps!
