Ok, disregard that Bonjour warning. Thats always there on windows.
Ok, so wired – ubuntu serves up to wireless laptops running XP. Right.
Ok, so firefly is working. I presume that the DAAP plugin is loaded?
Firefly can be set up to use avahi, or its built-in mDNS responder. For the latter case, it wont work when Avahi-daemon is running.
You can try and run avahi in a shell manually and see what pops up.
You should definetely see Firefly.
try something along the lines of:
avahi-browse --all
In a shell.
Give it a few seconds though, just to be sure.