I'm implementing SharePoint for a client, and they want it to be publicly accessible on their SBS box. As such, I installed SharePoint 3.0 and told ran the "Configure E-mail and Internet Connection Wizard" and told it to configure the firewall and to allow access to the Windows SharePoint Service intranet site. After that, things still worked, but when I ran the "SharePoint Products and Technologies Configuration Wizard" - it created the web site "SharePoint - 80" in IIS Management.
With "SharePoint - 80" in place, OWA does not work, nor does RPC over HTTP. In fact, with "SharePoint - 80" in there, the default web site shows as "stopped." When you try to start the default web site, it says "the process cannot access the file because it is being used by another process." Very strange.