This is most commonly caused by a misconfigured firewall. When you ran
the Network Setup Wizard, it enabled the XPSP2 Windows Firewall. If you
aren't running a third-party firewall or have an antivirus with
"Internet Worm Protection" (like Norton 2005/06) which acts as a
firewall, then you're fine but if you have third-party firewall
software, you need to configure it to allow the Local Area Network
traffic as trusted. I usually do this with my firewalls with an IP
range. Ex. would be 192.168.1.0-192.168.1.254. Obviously you would
substitute your correct subnet.

The other thing to do is understand that XP Home only authenticates as
Guest. If you don't need the ability to set fine-grained permissions on
your XP Pro box, enable Simple Sharing from Folder Options>View. In a
mixed OS network, I prefer to disable Guest (disable Simple Sharing on
Pro - you can't on Home) and instead create identical user accounts on
passwords on all machines. This takes care of authentication.

Then create shares as desired. XP Home does not permit sharing of users'
home directories (My Documents) or Program Files, but you can share
folders inside those directories. A better choice is to simply use the
Shared Documents folder.

If that doesn't work for you, here is an excellent network
troubleshooter by MVP Hans-Georg Michna. Take the time to go through it
and it will usually pinpoint the problem area(s) -
http://winhlp.com/wxnet.htm

Malke