On a LAN, you can often run into this: a computer with Win2000 has a shared directory enabled, but a computer with Win98 cannot access Win2000's shared directory. The answer can be found on Microsoft's official web page: it says just enable the Win2000 GUEST user.
But after XP came out, the same problem appeared again, and some people found that this method no longer worked. Accessing XP's shared directory from Network Neighborhood is not necessarily allowed. Why is that?
With the system Guest user enabled, click "Start" -> "Run", enter gpedit.msc, and the Group Policy Editor will come up. Under "Local Computer Policy\Computer Configuration\Windows Settings\Security Settings\Local Policies\User Rights Assignment\Deny access to this computer from the network", you can clearly see the Guest user there! If you delete the Guest user there, then other computers will be able to view this computer's shared directory from Network Neighborhood.
(Environment: Chinese WinXP, using the traditional logon method and with "Use simple file sharing" in "Folder Options" turned off.)