Why a ATA hard drive? Go with a SATA II, 16MB cache... great performance.
Seagate Barracuda 7200.10 ST3320620AS (Perpendicular Recording Technology) 320GB 7200 RPM 16MB Cache SATA 3.0Gb/s
$129.99 + $4.99 Three Day Shipping
If you're going with a single graphics card, go with the DFI LANPARTY UT nF4 Ultra-D
$123.99 + $6.67 Three Day Shipping
(There was one of these for sale in the B/S/T forum. $100, includes a Zalman 7000cu HS/F as well as shipping)
If you want the best performance, go with a CPU that has 2 x 1MB cache... 4400+, 4800+, Opty 165/170/175/180.
XFX is hit-or-miss. Either it will come screaming out of the box, or it will be a dud. eVGA is known around here as being the most solid, as well as for performance.