Maybe if you setup the network from the computer using xp with Network Setup Wizard and when the wizard is finished click on Create a Network Setup Disk and put that on a flash drive or floppy.
Install it on the other computers using vista and see if all the computers shows all the computers on the network.
What am I telling you is to install the network from the beginning, it only takes 5/10 minutes.
Post your result
Edited by Delta16, 24 February 2009 - 12:53 PM.