Don't worry about the PSU. Your 500W will easily drive new MB, 965 and a 5770/5870, so save the money 'till later
When you add another card and/or go overclocking, then you do the upgrade. Go for min. 750W.
Btw. the 1000W Fractal Design was sold at $150 - couldn't resist.
I have a ThermalTake 850W now, which is way enough to drive a Core i7-930, one 5970 and one 5870, but once the water cooling project is complete, I plan to go overclocking.
Cable management will take me at least a day to finish and would really, really hate to have to scrap it again just because the 850W runs out of juice under heavy load...
So in advance the $150 is already saved!
Your loading speed for SH3+GWX etc. will not be smaller by increasing GPU power.
Only more CPU power, more RAM and a faster disc will help you there... have you seen the "new" SSD drives?
