Small Business Server 2003
We got one of these for our office and it is just enough different that it is a little confusing to me. I kind of lost track of how Windows and Exchange worked with Windows NT and Exchange 4.0, so I date myself. Fortunately, "Microsoft":http://www.microsoft.com/technet/prodtechnol/sbs/2003/default.mspx has Technet which has lots of free information about it including how to plan and deploy it and there is the less useful "marketing":http://www.microsoft.com/windowsserver2003/sbs/default.mspx that tell me there is something obscurely named 2003 R2 coming out.
Our current configuration doesn't seem to work well, our client machines aren't in a domain and you can't find things via Netbios names, so on to figuring out what is wrong.