Benjamin,
The setup for a server you suggest is probably better than most on the message boards. A huge number of people are simply using a dedicated PC to act as their "Main computer" or "mini-server," on a peer-to-peer network.
A few of us have true client/server setups. The RAID 5 setup you are describing w/ single quad core should be more than adequate, as long as it meets the minimum system requirements for Windows Server or Small Business Server.
I am using a dual quad core system, 4GB Ram, 4 hard drive RAID 10.
Email me or PM if you want to discuss the server concept further.
