Need to setup a print server. Your pc can be the print server and the printer will be availbale as long as it is running. Use windows help files or buy a book like windows in a nutshell to find out how to setup the windows print server functions, once you do that, there should be a wizard on the mac for installing a network printer and more then likely a help file. If you have trouble getting the MAC to connect to the print server go to a MAC store and have the print server settings with you and they can show you how.
And not to leave out you can always buy a router that has a print server built in so you dont have to leave your computer on all the time.
-TL