Good luck with that 
Hey, Macs are pretty good gaming computers.
I mean, my macbook came with a NVIDIA Geforce 9400 M which is a pretty decent chipset.
In Bootcamp, which makes games slightly slower because Apple makes pretty bad drivers, I get 30-60 FPS on TF2, on medium/high settings.
It will also be nice to run TF2 in a native environment.