Another option for the case/PSU is the Coolermaster RC-531 with 430W PSU and side window for $99. The included PSU is of good quality. Look at the review on Sysopt.com
- it was done by our own Crashman.
You don't need ECC RAM - in fact non-ECC will actually perform better. Try this Patriot Signature Series
for less than half the cost.
Take the money you saved and get a eVGA 7800GT 256-P2-N515-AX
for $284 after rebate.
Edit: Fixed links.