I want to add one thing to gore's post. Regardless of which option you choose, if the home users will be connecting through dialup (less likely) then you should configure the server with a phone number to call them back at. This way, they'll log in, and the server will disconnect them and call them right back on the same line (and log them in).

It's done so that if user A steals user B's information, they can't log into the server because it will call User B instead of them.

If they're using broadband, then you can configure VPN's for them to access the server. I'm not familiar enough with them to walk you through that, but I'm sure you can find suitable programs to do it. Citrix or LogMeIN are two that I'm familiar with.

Have a great day
Patrick.