I have been doing PC tech support for 6+ years now and I still have problems getting Windows networking to work right (I call it "Microsoft Notworking"). Here's some other stuff to try:
-Make sure all PCs are in the same workgroup. Right click My Computer and click Properties. Click the Computer Name tab at the top. You can change it from here.
I knew there was something else I was missing as far as getting PCs to talk to one another. And that was it.
Thanks for the addendum, egrudzin.
Windows Networking is such a pain, and it really shouldn't...