Vista won't open xp networking

Please help me figure this out. I have a new Vista machine wired to an XP
(named "COMPAQ") via a Netgear router. The XP can open and change files the
Vista has shared. The XP can MS Easy Transfer files to the Vista and can
share iTunes music. The Vista cannot access the XP's shared files or shared
printer. In the Vista Network and Sharing Center, when I click on "COMPAQ" I
get the message:

"\\COMPAQ is not accessible. You might not have permission to use this
network resource. Contact the administrator of this server to find out if you
have access permissions."

What does this mean? Does "this server" mean the XP or Vista machine? I've
tried turning off both firewalls and matching names and passwords and redoing
the network setup wizards to no avail. I read
http://technet.microsoft.com/en-us/l.../bb727037.aspx but it didn't seem
to apply.
Please help!