New MBP, preformace for RTS games using Bootcamp

Im new to the forums so i dont know if i posted in the right place but i have a new MBP 2.4GHz IntelC2D ,2GB Nvidia GeForce 8600m GT. and was thinking about bootcamp to run my windows games. ex. Company Of Heroes and the new expansion pack comming soon. I was also wondering should i buy windows XP SP2 which is 32bit if im not mistaken or get something like vista with a 62bit any suggestions or help would be great! thanks