http://www.youtube.com/watch?v=PaPbXAZKol0

It plays from 05:20 onwards. Coolest music in the entire of DBZ if you ask me, but try finding the damn thing. If you can tell me the title I would surely appreciate it.

I'm pretty sure you can find that theme on one of the Best of DBZ CDs. I don't think it would be on the Trunks Compendium or the Buu: The Majin Sagas CDs. I could be wrong, though.

I believe that's "Destruction" (track 14), from Bruce Faulconer's 'The Best of Dragonball Z american soundtrack Volume 1'