Printer Scripts

Hey,
I have a script written to add the shared printers and making that printer
as default. Any user who logs on to Windows XP machine, They get the default
printer on their machines. But Windows Vista is giving me trouble. It wants
administrator's username and password for the first time. but if the user
changes the machine then go thru' the process again. How to get rid of this
u/name and P/word, so that users can get default printer on their machines??
Any Ideas or changes in script I have to do.. Please help?