My advice? Stick to Windows (or Mac) if you want to use pro-audio software like Propellerhead, Reason, Pro-Tools, Cubase, Ableton. That is what they're designed for. I am not flaming here but nothing in the Linux world comes close to these and Ubuntu is not a drop-in Windows replacement for them, with or without Wine. You are going to get varying levels of success.
I keep a Windows install to use these things, mainly Sibelius. You might try running Windows as a virtual machine inside Ubuntu but I don't know if I'd bother, personally. Good luck.
Yeah - sorry about the huge essay. Guess I was bored.
Linux is not a musical desert and there is a some good stuff out there for musicians. I use Audacity regularly. A great program - very easy to use - does what it does very well , although it probably won't do everything you want. Rosegarden is also really worth checking out. I've heard very good things about it but it is a lot more complicated than I need for the a cappella stuff I am involved in. There are quite a few good music sequencing programs which run natively in linux. Lots of programs to manipulate MIDI and MP3 and the like. From a musician's point of view the biggest problem with using linux is the lack of a decent score editing program. I've been using lilypond but it is insanely complicated trying to get it to typeset even simple musical arrangements. If you put in the effort the print quality is superb but it takes far too long to typeset a song and it doesn't give you the kind of "compose as you type" flexibility that I would like to have for my arranging.