OK, here are the details for those who may wish to try this themselves. The objective is to allow your Windows PC to print using a printer connected to your Mac, which is on the same network as your Mac.
1/ On the Mac, I opened System Preferences, went to Print and Fax and enabled sharing on my printer. 
2/ On the Mac, I went to System Preferences, Sharing, and disabled my firewall (this step may not be needed, but I was being sure firewalling issues didn't get in the way).
3/ On my PC, I went into the corporate firewall software and added my Mac's local IP address (192.168.1.2) to the "friends" list, so that the firewall would not block communications to the Mac. 
4/ On my PC, I downloaded Bonjour for Windows (get this from the Apple site at 
http://www.apple.com/support/downloa...rwindows.html), and ran the installer. Living truly dangerously, I didn't even restart the PC after I installed. 
5/ On the Mac, I turned on my printer - VERY important. This won't work if the printer isn't on apparently.
6/ On the PC, I ran the Bonjour Printer Wizard. A shortcut to it was placed on the desktop by the Bonjour for Windows installer. A window opened immediately and there was my printer, happily listed out and ready for use. I OK'd the preselected driver type (generic/postscript), and that was that. A few Windows progress meters popped up and disappeared as Windows installed the printer driver and then I was done.
7/ On the PC, I went to the Start Menu, selected Printers and Fax and as I mentioned above, there was my printer, ready for use.
8/ With fear and trepidation, I attempted to print a small Word document. Boom! It printed right away.
Apple makes things SO easy!!! I hope that this may make printer sharing easy for you too.