If you really want to spend that much money on an HDD I'd much rather set 2 or 3 WD6400AAKSs in RAID 0 than spend $1/GB of storage. You'd probably be just as happy with one WD6400AAKS and you'd have an extra $215.
Only on 790i, as far as I'm concerned.
You could go 2x2Gb of RAM to give yourself space to upgrade later. Also you will want PC8500 for overclocking.