Very basic network setup on XP

What can I say, I don't know what I'm doing.

My rooomate and I are both running XP and trying to setup a wired network. We've both both our computers feeding into a router with standard Cat 5.

We both ran the standard XP network setup wizard, and typed in the same thing for our workgroup. My roommate can see my computer and browse through my shared folders, but I cannot even see his computer listed under "view workgroup computers." Rather, I get the following message:

"Schmeerhouse (note: the name of our workgroup) is not available. You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions.

The list of servers for this workgroup is not currently available."

Does this suggest some sort of permissions have be unlocked? I don't know if either of us is the owner/administrator of this network since we both went through the same steps to set it up. I can't find anything in Windows that will allow either of us to manage this specific network/workgroup we've created.

Any ideas? Thanks.

I am running Pro, he is running Home. We both have SP2 and all the auto updates.

I have simple file sharing presently selected, but he does not seem to have this option under the same menu! Is this option only available in Pro?

Finally, I wanted to point out that I am unable to ping myself or his computer from the DOS prompt at the IP address my router has assigned me. However, note that we are both capable of accessing the Internet through our shared connection.