If you share the printer using windows shouldn't it show up when you browse for it on OS X? I know I see a ton of shared Windows printers shared in my subnet.
That "source code" is more then likely PostScript.
[Edit 2] After downloading and trying Gutenprint (was Gimp-Print) I now remember that my main problem is that I can't see my Windows PC on the network. Everything is set to share and the firewall is off so I'm not sure what to do.