Samba issues with XP

[pardsbane at offthehill.org (Josh Pollak)]

Ok, this is driving me crazy...

I've got a share on my Powerbook (OS X, running Samba) that I want 
guests to be able to log in to. Setting up user names for each guest on 
the PB isn't feasible, so I want any user who isn't recognized by the 
system to be logged in as a guest... This seems to work fine with every 
SMB client except Windows XP. I can't browse the Mac or see any shares 
from XP machines, but it works fine from Win2k machines.

Any idea what's going on? What did MS do to XP to prevent guest logins 
from working? I noticed that you can leave the username and password 
lines blank on XP anymore, is my system sending some wrong signals 
making XP think guest's aren't welcome?

I hope someone can help...

Here is my smb.conf file:

[global]
guest account = unknown
encrypt passwords = yes
auth methods = guest opendirectory
passdb backend = opendirectorysam guest
printer admin = @admin, @staff
server string = Mac OS X
unix charset = UTF-8-MAC
display charset = UTF-8-MAC
dos charset = 437
use spnego = no
client ntlmv2 auth = no
workgroup = OFFTHEHILL
browseable = yes
guest ok = yes
hide dot files = yes

[homes]
comment = User Home Directories
browseable = yes
read only = yes


[Public]
path = /public
browseable = yes
public = yes
guest ok = yes
writable = no
printable = no