I wouldn't put my file server in my attic. It gets pretty hot up there in the summer (>100 F), and cold in the winter (<-10 F). I keep mine in the basement.
I also don't see the need for high priced equipment for it. I have been using a Compaq Presario 5000, 1GHz AMD Athlon CPU, that I got out of a recycle bin. I put the latest version of Fedora on it, which was Fedora 8 (1997), and it has run fine ever since. I did just replace it. I had an Atom/ION HTPC that I stopped using because Atom CPU's can't play flash video, and my HTPC must be able to play flash. I finished setting it up about a week ago, and the Presario is now turned off.