I would go with a dual channel pair of DDR533 RAM so you get a 1:1 FSB:DRAM ratio with the 1066 MHz FSB. the 667 MHz RAM won't any faster because of the latencies.
Doby has found a very nice PSU, I back that choice. You will want a good quality power supply to hold up that system. If you do look at the 8800, then be prepared to look at 700+ w PSUs.
I would get this hard disk:
http://www.newegg.com/Product/Produc...82E16822136062
16 MB cache, and twice the size.
If I had the money, I would actually get a 36 GB WD Raptor and hook the 160 GB up as a slave. I would have a very fast hard disk if I did that. But if you don't have enough $$, just go with the 160 GB. Mass storage has gotten very cheap, and the 160 GB won't be that much more expensive than the 80 GB.