For a ten user network, you can get away with just whipping a basic server from Dell for a few hundred quid (we bought some at work for less than 300).

I'm not a Windows advocate, but if it aint broke, don't fix it. If you have experience with Unix, Linux *nix, go that way - you'll feel better for it

Otherwise, stick with what you know. If you can, try and find someone who'll install Windows 2000 Server - it's smaller, and less lardy than 2003, but just as capable. For what it seems like you need to do, anything else would be a waste. In fact, if you're gonna have no more than 10 pcs, you could just get away with another copy of Windows XP or 2000 Professional, as they have a limit of 10 concurrent connections.

All you need is a big disk (better to have two, in RAID 1 to keep your data safe), and a nice high capacity tape drive...and lots of tapes!

Get yourself a nice 12/24 port 10/100MB HP switch, with a 1Gb port (and 1Gb network card in the server!) so that all the clients have a pretty much guaranteed 100MB link to the server.

Got plenty more advice if you need it.