Hey guys.

I currently have a pretty decent PC I just built this fall. I want to dual boot OS X on it though, since that is what is used a lot in web design/development, which is what I want to get into after college. I'm trying to spend as little as possible but still be able to game as well as I can now on windows.

Right now I have an AMD processor and AM2 motherboard. My graphics card is an Asus HD4870dk.

The Mac Pro supports ATI 4870 so I should be good for that, right?
Can I get away with just upgrading the processor and motherboard?
I am thinking of the Q9650 and GIGABYTE GA-EP45-UD3P, since I am already a fan of Gigabyte boards.

By the way, does OS X have any restrictions in place to prevent overclocking?