Printing via Airport - Can't Make it Work

I am running OS-X 10.6.2, Parallels 5, and Windows XP on an iMac and a MacBook. The MacBook connects to the internet and to the printers connected (via USB) to the iMac. I can print from the MacBook with OS-X software with no problems. I cannot print from the MacBook with Windows software. I tried all the things I could find in the Parallels Help files, with no success. When I tried Bonjour, it opened, listed the two printers that are connected to the iMac, then told me that they were unavailable when I selected one of them for connection.