Ephraim J. Witchwood said:
Ephraim has basically hit it on the head (Even though they suggested AMD, evil!)
Those are probably the minimum specs you are looking at. In fact I will be building a friends computer with very similar specs to this over the weekend. =3
The one thing I don't necessarily agree with is the multiple HDDs thing. (Not that it's an issue, HDDs are one of the cheapest parts for a computer unless you are getting SSDs) You can run off one HDD perfectly fine. if you are worried about the need for reformatting, you could always make (Or get someone to make for you) a backup image/self restore for your drive.
You could even partition your HDD into OS/Other halves to make this even easier.