My two cents
Pro tools needs a Nvidia based video card, check the requirements page.
As for the HD for recording I'll spend a little more and buy one rated at 10,000 RPM
Before buying the memory check that is on the aproved vendors list for that motherboard. Asus tends to be very picky about the memory.
One thing you didn't stated was the cabinet/enclosure. Buy a large one so the heating problem won't be a concern.
Also you'll need a 64 bit OS, Win 7 Professional would be my choice.
Now I am a PC numpty but it seems unlikely to me that THE major DAW software would be limited by what video card you have?
Then are not 10k rpm drives noisier for no real speed advantage over a modern SATA 7.2k which IIRC can run at least 100tracks at 96kHz?
Dave.