i get that too. before my dad switched to xp all was fine. now i get the same error message as you. i cant figure it out off the top of my head, however i do admit i havent really looked that hard at sambas website....yet!
try adding :
lanman auth = no
min protocol = NT1
to the global section of your config file and let us know what happens!!
EDIT:
what am i thinking? this is for client side config. im still in the dark aswell. what i said shouldnt do anything to help you.
you SHOULD be able to install the client side only samba tools to print to a windows computer. this is what i have done, as i have no need on my desktop to share files via SMB.