This is what I'd recommend you to get:
Opteron 165 s939.
DFI Ultra-D (try to get the AD0 revision, those seem to OC noticably better, newegg supposedly now sells them)
Gefore 6600GT or Radeon X800(GT). the X700 is slower than the 6600GT, the 6600GT is slower than the X800(GT), especially when both are OCed.
The HD of your choice, I don't know about NDX_WARLORD, but my Maxtor 80GB DM8 is working like a charm for over 3 years, mostly 24/7 too.
I'm guessing you're planning on sticking with the RAM you currently have? It'll be fine for now.
I would also recommend you to get a new PSU, Generic stuff just doesn't cut it when it comes to A64 OCing. A good and relatively inexpensive option is the Fortron BlueStorm 500W.