64 x2 5000 problems

so right now I'm running xp with a 4670, 4gb of ram, x2 5000, and a rando seagate hd.

sometime when im playing a game the cpu will bottleneck the gpu, i know this because in wow when im doing a 25 man raid i get the same fps in the highest or lowest settings, and when i check out my cpu it usually is it between 60% and 99% usage...which it shouldnt be.

someone told me it was because i was running a 64 bit cpu on a 32 bit os, which i thought sounded ridiculous. I was kinda waiting to get a new hd to upgrade to the w7 rc or vista (free) but would it be worth it upgrading now to see if my cpu will work better? because it REALLY shouldnt be doing this, its like it only has 1 core or something.

and i cant even oc it because its not the black edition

please help! thanks

If the computer is not OEM, it should be able to overclock, even though its not a BE AMD CPU. You can raise the FSB, that should give you a little increase.