ahh, I think I've gotten to the bottom of it, only because I've had the same problem myself:
find out the computer name of the computer that is sharing the printer.
Windows 2000/XP: Right-click my computer > click properties > click "Computer Name" tab.
Under "full computer name:" It says your computer name.
Now go onto the guest computer (the one you want to be able to print from, but doesnt have the printer hooked up to it), open up internet explorer, and in the address bar and type in \\name
(where name is the name of the computer sharing the printer)
It MIGHT ask you for a username/password. Enter any username and password that is being used on the computer with the printer. Try "Administrator", with no password, that might work. If not, find out one of the usernames/passwords of that computer and enter it in here.
Now you will be connected and see everything that computer is sharing, including the printer.
Right-click on the printer, and click on "connect". It will install drivers for you and do everything that is necessary.
If you had to enter in a username and password, this is not such good news. I don't know how to avoid having to do this every time (though I will make a thread about that myself, be on the lookout for it). In the meantime, again, only if you had to enter in the username/password, every time you wish to print to that computer, you will need to initiate the connection. Do this by going to internet explorer, typing in \\name, entering in the username and password. You are now connected. YOU DON'T NEED TO RIGHT CLICK ON THE PRINTER AND CLICK CONNECT. THE PRINTER IS ALREADY INSTALLED. Once you have properly put in the username/password, just close the window, and print.
hope that helps...