1. Both computers need to have shared something, a folder, and/or a printer.
2. Both computers need the Guest account turned on in Control Panel, User Accounts
3. Both computers need to be made members of a Workgroup, with different computer names but identical Workgroup name.
4. When prompted at startup, you must hit enter or Okay to login. Hitting Cancel or the Escape key will deny you access to the network.
5. It is generally recommended that User #1 add User #2 as a user on the Computer, and User #2 do the same for User #1 on his computer.
Once this is set on each machine in My Network Places hit View, Refresh. It can take several minutes to fully populate the Neighborhood display as the Computer Browsing Service on each computer discovers the existence of the other.
Once discovered their existence will be persistant.
Whle you do not need Netbui in this setting, there are some tricks to setting it up properly for Windows XP. One idea is to use the Win2k version of Netbui under XP. There are other tricks. Please see this article for a discussion: