Don't forget the simplest thing overlooked in any windows xp to windows vista or 7 network is that ALL computers MUST have a password on the user accounts otherwise windows vista will not allow access to the available network shares or workgroup.
Other issues with windows xp home include a failure to correctly register new computers on a network, this can usually be resolved by opening up a command window, start->run->cmd in xp or all programs->accessories->command prompt for windows vista or 7 (**right click and select run as administrator on command prompt).
once the command window is open type;
ipconfig /flushdns press enter, then ipconfig /registerdns press enter again then restart the computer.
this will usually correct issues when opening workgroup.
other things that may help, you can usually attempt to connect to a computer by opening up my computer and typing \computername\sharename into the address bar. if it asks for a user name and password use a login and password from the computer you are connecting to that has access to those resources.
Best of luck.
They have a wireless router with DHCP. Do I have to turn on file and print sharing and designate shared folders? – foosion – 2009-11-13T15:21:08.833
Yes you will have to turn on file and print sharing Heather has a good point. I am running it on my home network with 5 Xp , 1 Vista , and 1 Win 7 computers. but all are running the Pro versions. I also have never set this up with the home versions. – Boxdog – 2009-11-13T15:35:05.433