Just to be sure - have you designated drives or folders as shared resources on both computers?  Are you sure that the XP firewall is disabled on both computers, or, if you are running any third party firewall software, that the the firewall has been configured to allow local network traffic?

Steve

The Norton firewall has a way of messing things up, even when it is not enabled.   Either configure it properly to work with the network, or stop it from running at startup so that it never gets loaded while you are troubleshooting the problem.  Once you get the network to work, you can restart Norton and configure it to work with your network.

Steve

You could check to make sure you are logging on correctly.  If you are not logging in as the name of the computer (if you have multiple users,) then each computer may not see the other on your network.

Just to add to the discussion, check this piece of information:

http://www.theeldergeek.com/quick_guide_to_simple_file_sharing.htm