*tiny* SOHO fileserver upgrade recommendations in 2012? [closed]
There's no single recommendation that works in all cases. I'd seriously look at an entry-level HP ProLiant or Dell server that either comes with a Windows server license or is verified to work with it. On the HP side, a ML or DL 100-series is good. Buy a unit with enough RAM and a real hardware RAID controller/solution. Any modern CPU will have the requisite horsepower for this task.
I'd scrap the idea of building anew. The packaged servers are so inexpensive that it doesn't make sense.