[Samba] attaching printer w/user level sec; XP okay, 2k won't work

[VaX#n8]

So I've spent a couple of hours on this and I think I've found the problem.

I have cups and samba running on the print/file server.
I have a 2k and and XP system as clients.
All are in the same workgroup.

I started with share-level security, and everything worked okay.

Then I decided to tighten it down a bit, and moved to user-level security.
XP could connect to both the printers and file shares just fine.*
The 2k machine can connect to the file shares, but not the printer.
Instead of prompting me for a user/password, it just says "Access denied".

Also, browsing seems broken.  The print/file server just isn't showing up
in the network neighborhood.  Could be a seperate issue.

[*] Actually, if I connect to the printer and bring up the printers menu
on XP, it has an error in the "Status" field (I think Access denied), but
it can print just fine regardless.

Any ideas?

Also, do the users in smbpasswd file have to have Unix accounts?
I'd like a user just for connecting to printers, who won't own any files.

Thanks in advance.