The article didn't address my problem but in following the steps for password protection I realized that Dell Support Center had recommended in one of it's "alerts" that the guest account be turned off.  As a result a password was required to access the XP pc.  I turned the guest account back on and the requirement is no longer necessary.  Thanks for pointing me in the right direction.
i just connected my new Dell XPS 420 running Vista Premium to my Dell Dimension 8300 running XP SP2 through a wired linksys router. I've changed workgroup names to be identical and enabled sharing.  The XPS 420 replaced an older Dell Dimension 8100 on the network.    The Dimension can access shared files on the Vista machine with no problems but when I try to access files on the Dimension 8300 from my XPS 420 I am asked for a user name and a password.    I don't know what user name or password it's asking me for but would like to disable this requirement.  Any ideas on how I might do that, or if I can't disable this, what user name and passwork it might need?  My 2 pc's aren't password protected.  Thanks for any help.
Password required to access home network