UnableToGetPrintingWorking

First off, I'm not sure if this is a gNewSense problem or a networking problem - I'm a bit of a newbie at both. So here goes:

I have a firewalled network set up, with two Ubuntu machines (mine) and one Windows XP machine (my father's, pegasus), which has a printer connected to it. Within this network is another, also firewalled, network that has a gNewSense machine in it (arya). I want to print from arya to the printer attached to pegasus. As far as I know the only practical way to do this is via Samba. So I run the printer configuration utility, but it can't find any Samba printers. I've tried entering the URI manually but that doesn't work either (it doesn't protest when I'm setting up, but it doesn't print, either).

Any suggestions? If it's a networking issue, can anyone suggest any reading recommended to better understand the basics?

Thanks a lot, Sharif