XP can see vista but Vista cant see XP

I have two PC I would like to network.
Vista Home Premium
XP Media Center
From my XP PC Vista is shown as a workgroup computer and I can access,
delete and add files to Vista’s public folders but XP is not shown on under
Vista’s network computers or under full map. Other devices connected to my
network (media severs, router, etc...) are displayed in both locations.
Some trouble shooting methods I have tried:
• Confirmed both PCs have the same work group name
• Disabling an enabling firewall (windows firewall)
• Turning on and off password protection (Vista)
• Creating the same user name and password on XP machine
• No need to download LLTP hot fix XP machine running latest service pack
• I am able to ping both machines from each other
Any other trouble shooting methods will be greatly appreciated.