Inability to share files on an XP computer with a VIsta computer on network

I have a desktop running XP Media Center that is directly hardwired to the router. I have a Vista desktop connected to the network via a wireless G card. When I am on the XP computer I can access the files on the Vista computer. When I am on the Vista computer and run Network Map I see the XP computer only when I click "View Full Map." However I can not access the files on it. All computers share the exact same workgroup name (changed 3 times). Any ideas on how I can access the XP files on the Vista computer. I have gone to the XP computer and allowed file sharing. I appreciate your assistance.

 

Issue still persists

I did go through all of those steps and I still can not get access to the XP files on the Vista computer. I have also turned off the firewall on the XP computer and still the problem persists.