Even if activating the guest account is a correct moves, it is always suggested not to activate the guest account for security reasons. As shown in the previous replies, you can create a local account on the win2k box, with same username and password as the one used on the winme box, if you don't want to get a request for password.
If not, make sure you map your network drive (on the winme) by specifying the username and password of the win2k box. By default, you can use the administrator account if it asn't been renamed.
Or, using a command prompt, you can use net use to access the ipc$ share and specify the user account to use before being asked for the password, here is the command line:
net use \\computer_name\ipc$ /user:username or on a domain
net use \\computer_name\ipc$ /user:domain_name\username
net use \\computer\ipc$ $user:administrator
Note that the IPC$ share is use to help you run a local software on your computer and access the ressources on the remote computer as if you where logon locally !