I am really puzzled. I had upgraded to Tiger -- no problem, got everything working great. Had gone ahead and upgraded 2 PCs to XP -- took a bit more work, but everything was working fine -- everyone could see everyone, everyone printing to everyone.

Now all the sudden, one of the PCs can't print to the Canon i960 hooked up via USB to airport base station. Both the mac and other PC can. I looked through all the firewall stuff the windows machine, I compared it to the one that was working, I deleted and added the printer. And by the way, do have windows bonjour installed and doesn't see it.

Interestingly, the same PC that can't print to the i960 can print to the printer attached to the other PC. And the other PC can print to the i960.

And, by the way, my work PC which was recently upgraded to XP and HAD been accessing the i960 fine through Bonjour also now doesn't see it through Bonjour (I did try reintalling on both computers as well).

My hunch is it has something to do with the last security update (I did both of them) since it has been since then all this happened.

The only thing I had done differently is install the latest security updates for my mac (powerbook g4).

Think that provides the landscape -- this has got me really stumped!
On the pc in question have you used 'restore' to a date and time to when it was working? I'm not sure if that will solve the prob but it's worth a try.