Sharepoint Server

First of all, anyone using Sharepoint server?

Also, if I were to purchase Sharepoint. Is this something I can install on an existing Domain Controller or Exchange Server? I do not want to purchase an additional server and Server 2003. We would only have 10 or so users.

Thoughts?

You cannot install Sharepoint Portal Server on a server with any version of Exchange. Windows SharePoint Services can however exist with Exchange on the same server.
This link gives a good breakdown of which applications can coexist on the same server.

Thank you for the document. It appears this does not apply to SharePoint Server 2007. I did not see a page for the 2007 version. Any ideas?

According to a Wiki:

Microsoft Office SharePoint Portal Server is an enterprise portal which belongs to the Microsoft Office family. In the 2007 release (version 3.0) the word 'Portal' is dropped and the product is called Microsoft Office SharePoint Server 2007 (MOSS 2007).

Maybe MS combined the portal and services in 2007 version?