Yeah, a dedicated home server is quite useless. I just set up one of my working computers to work as a simple home server on the side. Just run Samba, have a second HD to hold the info, and keep up with it. However, I'm typing from this 'server' right now. I couldn't imagine having a dedicated headless server for fewer than 15 computers, though. Just seems worthless,
IMO.
Also, my 'server' is made from old parts, running linux. So I didn't even spend any money on it. Just a few hours getting it set up properly (about the same amount of time you'd probably spend on a WHS), and it's good. Samba is damn easy if you know your way around smb.conf.