I have these parts already:

BFG nForce 680i SLI mb
BFG 8600GT OC GPU
2Gb DDR2 PC6400 ram
Case, fans, etc.
750w PSU

what kind of HD, DVD and processor do I need to have a basic setup that will work?

well idk about the 680i chipset... i don't think it is the best chipset for OS X but the Q6600 is good if it is in your budget and for HD and DVD i think any will do
i know that is true of the HD and fairly sure it is about the DVD. do some research on that too. but HD any make sure it is the right kind (SATA or ATA)

The mb has SATA connections. Does brand matter on the HD and DVD?

Which install do I need? There are so many on these boards it is confusing for a hacknoob.

Brand dosen't matter specificlly with a hackintosh but you want to get a good brand that has a history of reliablity, seagate is a good one, I had troubles with Western Digital.

MAKE SURE THE MOTHERBOARD IS COMPATIBLE!!!!!
i don't think the 680i can use pc EFI
really look into it!!!
or it could be a waste!