In case of Vista
Right click on the Computer Icon
Choose properties from the drop down menu
Under 'Computer name, Domain, workgroup setting.
Click on change setting.
Then the computer will promt for user permission
Click on continue
Then a system property window appear
Under Computer Name Tab
Click on change (To change the computer )
Do not change the computer name rather only change the workgroup as MSHOME.

Then the system will prompt for restart.
Restart the computer and follow the following steps


Open the control panel, double click the Network and sharing centre. Under Sharing and discover tab
turn on Network discovery,
turn on File sharing,
turn on Public folder sharing,
turn on Printer sharing, (If you have any printer)
Turn off password protected sharing

After that you can re run the network setting wizard in the machine having XP.

Thats all
You are done.