chris is right, i have a similar set up . i have a printer on an xp machine shared. i have redhat on another machine. first make sure that the printer is shared, then go to control center=>peripherals=>printers=> administrator mode=>type in your password . after that follow the instructions.
another method is
open your web browser and go to http://localhost:631
then click on printers=>then add printer. then is going to ask your for user name and password, make sure u type root for username with the appropriate password. enter a name , location, and description of your printer and click continue. in the next screen you need to select printer via samba. next you will need to enter the uri , the following is an expample
assword@Server/Printername; if i remember correctly, username is the username on the xp machine, password of the same user, Server is the name of the xp box where the printer is attached. hope this helps,