My Macbook Alu 08 was a fantastic gaming companion (Along side with the best work companion I have ever used, and I have worked with loads of machines).
It has a 2.0 GHz CPU with 2 GB of ram and a brilliant 9400m.
Here are the games I used to play on it:
Garrys Mod (I used to love that game. Played it allot maxed out perfectly)
Minecraft (Maxed out perfectly, but now, my Macbooks Logic Board is failing I think so the performance on everything is going down.)
CSS (Same as Garrys Mod)
Terraria *Perfect*
GTA 4 (Very very playable on low settings @ 800 x 600)
A little bit of game dev (which it did fine)
WOW worked fine maxed (I think)
This was all under boot camp btw. I did try some of these games (Gmod, CSS and Terraria) but they only run very well under Bootcamp, so if I where you i would stick to bootcamp.
Anyway, thats that. I would wait for a MBP with a dedicated GPU.
Thats your best bet. Its sad really that Apple put the HD3000 in the new 13 Macbooks 🙁 (I have heard they arent as bad as people make them out to be, but my freind had a Acer laptop with one in and it was pretty awful).
All this is my own opinion and experience.
Anyway, thats all.