Does it have a USB and Parallel port? If the 2 computers are near each other, you can plug the PC into the Parallel, the Mac into the USB. If you have both on DSL, do you have a router? Some routers have printer ports, but for some reason they can't be networked through the Mac.
If you want to go wireless, there are a couple of ways you could do that, but sometimes it's cheaper to just buy another printer. I know Epson has add-ons to make some of their printers networkable (wired and wireless), but for the same price you could buy yourself 2 or 3 C82 InkJets.
There is a way to network a USB printer between Macs, I'm not sure how to do it with a Mac and a PC (if it's even possible). Normally, I'd try
http://www.xlr8yourmac.com or Apple's Knowledgebase, but I don't remember seeing it anywhere.
What kind of setup do you have? What kind of setup are you looking for? I think we can help you more if we had some more info.