Guys just because the task manager says that both of your processors are being "used" by BF2 doesn't mean that BF2 is taking full advantage of dual core or quad core processing. BF2 was not optimized around dual core processors since they didn't exist, thus, though it uses both, it doesn't use both to make the game run smoother, ie, breaking up tasks to run on certain processors thus making the overall load lighter.
It really still (generally) treats the game like you only have a single core CPU. You might have a slight performance boost for having two, but certainly nothing like a game that has been made for dual or quad core CPU's.
