Looks good. Your choice of CPU is pretty good, in terms of assessing the L2 cache amount.

I think twice about the Radeon HD 2900 XT though. True, it's difficult to get good cooling for the GeForce 7950 GX2 because of the way the processors are stacked (a kludge if ever I saw one), but it's overpriced, power hungry, hot and imbalanced. Better off getting GeForce 8800-series if you don't want to be stuck with the GX2.