This is most commonly caused by a misconfigured firewall. When you ran the
Network Setup Wizard, it turned on 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 iIf 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.

If one or more of the computers is XP Pro:

a. If you need Pro's ability to set fine-grained permissions, turn off
Simple File Sharing (Folder Options>View tab) and create identical user
accounts/passwords on all computers.

b. If you don't care about using Pro's advanced features, leave the Simple
File Sharing enabled.

Simple File Sharing means that Guest (network) is enabled. This means that
anyone without a user account on the target system can use its resources.
This is a security hole but only you can decide if it matters in your
situation.

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