Samba is probably the best answer for this dilema. There is a lot of good documentation out there for setting up Samba to share printers over the network. Ubuntu might have a graphical configuration utility for Samba, but I'm not 100% sure on that.
A good start would be to install samba by either typing "sudo apt-get install samba" in your console, or using adept and installing the packages that way.
Here is the official "HOWTO" guide for configuring SAMBA