Now I understand
My mistake I thought you meant that multiple machines was a option you were exploring not that you already had. I have setup the WD NAS box for a few people. They use the 1TB system (2x500GB drives), which we setup in a mirrored pair (500GB available). It connects to the router with Gig-E, and can even be wireless (but slow this way). No software is required for windows or mac. If everyone using this can see everyones data you are done. If not then you need to setup access controls. But since this is home use just create a share (folder) by user name.