New wireless Vista can't access networked printer thru XP PC

Have a new laptop with Vista, trying to set up use of home networked printer
which is attached to a PC running XP. The shared printer appears on the
laptop and the laptop shows up on PC as part of network.
When marking "Printer Sharing" in Network and Sharing in Vista, "(passwork
required)" appears next to "On". I don't think I have a password but, even
so, Vista never prompts me to enter a password and when I click on the shared
printer the error message is, "Windows cannot connect to the printer. Access
is denied." I can't figure out what to do.
Thanks -
J's Mom