I have a wireless vista 32 which cannot see other xp units wired directly to the wireless router. All units have "WORKGROUP" as their name group. Xp units have shared their file folders openly. The router is not secured. The router has been reset (wrt110) and units rebooted. The xp units talk to each other fine.
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it can be because of the Antivirus and also the firewall that are not allowing the Vista to comunicate with the XP computer
did u set your vista machine and sharing center to home network and make sure it is set to share!plus 1 for the firewall as stated above!