If you really want to play hard core Windows game in windows (on a Mac with BootCamp installed ) then I would urge getting a Mac Pro. This way you can get the latest games and they would play a full speed.
The one thing is I would wait one month for MacWorld in January. Apple may refresh the processor lineup then.
Mac Pro Dual 2.8 Quad (2nd gen), 14G Ram, Two DVD-RW Drives, OS X 10.8.3
2006 Mac Book Pro 2.16 (first Gen) OS X 10.7.4
2TB Time Capsule, 2 TB
32G iPhone 4S Black, iPad (3rd Gen) 32G Black