Here's my scenario. People show up at the house with PC laptops and want to print something. A boarding pass, an email, a web page. They screw around with Windows control panels trying to find the printers on my Mac network. In my case, they are both shared on a Mac Pro.
Enter Bonjour. It's the Apple answer to zero configuration networking. All you have to do is download Bonjour for Windows. There's also a 64-bit version if you need it.
Once it is downloaded you'll get a Printer Wizard, which will instantly find the printers available on your network, including the shared ones. (Make sure you are sharing them in the Sharing pane of System Preferences.)
Now when your guests want to print, they will be all set. No other drivers are needed. I now keep the Bonjour for Windows .exe on a thumb drive. I hand it to guests, and they are ready to roll.
Bonjour can do more than discover printers. Per Apple:
Bonjour for Windows includes a plugin to discover advertised HTTP servers using Internet Explorer. Click the Bonjour icon in the Internet Explorer toolbar to enable Bonjour browsing. If you have Bonjour devices on your local network with embedded HTTP (Web) servers, they will appear in the list.
It's possible you have a printer that doesn't support Bonjour, but most do. In my case an Epson and a Brother laser printer worked with no glitches. Bonjour requires Windows 2000/2003, Windows XP or Windows Vista.
If only everything in life was this simple.