Does anybody know if it would be possible to run FreeNas server on a dell dimension server with 2 80GB hard drives. I'm just testing this procedure and will upgrade the hard drives to 1TB in a few months if this works.

Does anybody know if it would be possible to run FreeNas server...

I've never used that particular hardware platform, but most Linux based things can be made to work on anything with a little effort. The easiest way to find out what issues might be encountered is to burn and run the FreeNAS Live CD on the 4600 and see what happens. The Dimension 4600 is a desktop machine and wouldn't be my first choice for a reliable server. Also to do hardware RAID, a hardware RAID adapter would need to be installed. Most of the well supported big name RAID adapters (Adaptec, 3ware, etc.) are currently PCIe or PCI 64-bit. The Dimension 4600 is getting a bit long in the tooth and the specs (http://support.dell.com/support/edocs/systems/dim4600/en/4600/sm/specs.htm) indicate only three 32 bit PCI slots. Your choice of RAID adapters will be constrained.