The software on my Airport Extreme was recently updated to the newest firmware (v5.5.1). All the Macs that were unable to print to our Epson Stylus Color 740 suddenly started working after this update, but all of the Windows XP machines in the house stopped working. I tried setting up IP printing, but nothing seemed to work even that way (in WinXP or MacOS X). To solve this, I posted on the forums and got a suggestion to try Rendezvous, so I downloaded
Rendezvous for Windows Technology Preview 3 from Apple's Developer website.
Installing it requires a restart, but afterward, there is a shortcut on the desktop to setup a printer. I did this and noticed in the process that Rendezvous automatically detected 9101 as the raw port instead of the default 9100. It worked beautifully! I even went back and set up a printer with IP printing and used raw port 9101 instead of the default 9100, and that worked! So you can use port 9101 or Rendezvous to achieve the same thing.