Acting as a host.

[Eric C. Head]

There are other departments in our county that are interested in having us host their website for them.  Currently we only have one NT Server acting as our webserver.  I would like to be able to register and set them up with their own domain name instead of it being a /subdirectory of ours.  I'm interested in the details about how sites do this sort of virtual hosting.  Any help or pointers to resources regarding this would be greatly appreciated.  
If you respond to me directly, I will summarize for the list.  TIA

Eric C. Head
erich at cclib.org
http://www.cclib.org