Share Mac printer with Windows PC

1. Find the workgroup name on the Windows box (press Windows+Pause/Break)

Add the workgroup name to the Mac Wins settings.

Click "Network"

Click "Advanced"

Click "Wins" and type in the Workgroup name.

2. Make sure Bonjour is installed on the Windows box. Bonjour is included with iTunes.

3. Make sure Mac printer sharing is turned on.

Full instructions here from About.com