Hard drives don't effect performance, only load times, however you want reliability with a hard drive, or in laymens terms, you don't want it to fail. Maxtor has a reputation of failing fairly quickly, and Western Digital and Seagate are the opposite, they are very reputable companies that build good drives that aren't prune to failure very easily.
A few things, first I suggest switching the fatal1ty with the DFI Lanparty nf4 Ultra D or SLI-DR, these are the best socket 939 boards around for anything right now, and DFI really does an excellent job of looking out for the customer. I was talking with someone here yesterday about the nf3 DFI board, and they were determined to make sure the board lived up to really high expectations before they release it. That's how far they go for the consumer.
I also recommend the 3200+ with the Venice Core rather than the Winchester. Venice is newer, has added SSE3 instruction support and edges out the Winchester slightly in about everything, while using less voltage and staying cooler at the same time.
Memory, I don't really like Corsair memory as they are overpriced and overated. Try this stuff
About the variations of the 6800 line:
6800 - 12 pipelines, lower core and memory speed, basically low end, stay away from it
6800GT - 16 pipelines, "normal" core and memory speed, this is what you're looking for, the best overall performance
6800 ultra - almost the same as the GT, except with slightly faster core and memory speed. Not really worth the price
And stay away from the LEs or whatever they call them, they are "broken" 6800GTs that have pipelines disabled and clock speeds lowered.