Can I have multiple domains on one Windows Server?

I have Windows Server 2003 running on a roughly 7 computer network. I am learning everything as I go. Networking is not my strong suit, but I know enough to know what I don’t know… usually.

My question is this: right now the server is “Server1” and it does various things for us, but I would like to have a domain “XYZ” that would run our intranet. Now, I know I could make a simple little $300 box or some old computer and run LAMP on it baddabing, but it would be easier if I could just have that second domain on one box.

Any suggestions?