I did a blog post about Tuxguitar a few months back. However, I did discover in Ubuntu that the default MIDI port does not seem to work, and you get no sound at all from the program.

Fortunately this is fairly easily remedied if you have Timidity installed. If you do not, install it using:

sudo apt-get install timidity timidity-interfaces-extra

Once you have it installed, simply go to tools>settings>sound and change the MIDI port to Timidity Port 0 #1. Now most of the sounds should work, with the possible exception of the synthesized sounds (e.g. Syn Saw Wave e.t.c)

Another note, you cannot have another sound producing program running while having TuxGuitar running, even another instance of Tuxguitar, as one of them will not work.