There are two steps: first share a printer, then use a shared printer.

In Ubuntu, you go to Administration/Printing on the host computer as your
starting point to share a printer. (This might have moved around from version to
version.) After a click or two you give it a name, and you're done.

In Windows, it's Control Panel/Printers. You also have to ensure that File and
Print sharing is enabled in the network properties.

To use a shared printer in Ubuntu, begin at Administration/Printing and select
"new," network printer. With any luck, Ubuntu will discover the printer(s) you
want and it just takes a couple of clicks to install it or them.

This somewhat depends on how good the vendor's support is for Linux. For
example, a couple of years ago, it was almost impossible to get any Lexmark
printer working, but Lexmark has turned 180 degrees in its Linux support.

I have a Brother laser printer attached to my router, and installation on Lucid
or Maverick takes about three clicks.