can be done!!!
this has taken me aggggges to figure out so i thought i give a few pointers to anyone who might be stuck with this,
when your adding a new network printer to the list - you may have set, like me, on your winddows xp box - no user and pass for sharing network resources, so when you come to add the printer to the list you can do this without requiring a user name and pass,
but when you come to try and print XP will refuse to print because your not using any user or pass. The ansswer is when your adding the printer in network neighbourhood>mshome> menu and then select the name of the XP machine, and it asks you for a user name and password, rather than leaving it blank you must enter the name and password you use to log into XP (probably best to use whoever is admin user) - this should solve the problem
AND - add the macs IP to your trusted/allowed section on your firewall
AND - goto control panel>add remove programs> add remove windows components and make sure the network printing stuff is turned on
hope this helps someone -
this is possible - but can be a nuisance - and would you believe the problem always seems to be windows XP and not OS X!