I have a case from a rack mount UPS which looks like it could happily hold a bunch of drives and is deep enough to hold a few other things. I want to build a computer in there to host some drives. basically I'm thinking it will need PCI for a SATA card, and gigabit ethernet. Besides that, I want it to be able to share via AFP and ideally use Bonjour. It will need to run either software RAID or have a compatible low cost SATA RAID card available, and run VNC, preferably to work with Apple Remote Desktop.

I figure this leaves me the option to run some flavour of Linux, or try to build a hackintosh. Will Linux run the services I want?
I'm looking for suggestions for both sotware and hardware solutions. I need the smallest board possible which has plenty of SATA ports or expansion slots for them. Overall system speed and CPU are not immensely important. Something a year or two old will probably suffice. The point is to do this as cheaply as possible. I'm not looking for Xserve RAID performance. I just want to be able to hold large amounts of data with redundancy and the hardware needs only do a reasonable job of keeping up with gigabit ethernet. Its for streaming media across a local network and keeping it safe.