here is a list of where you can get trials of the different music applications

WINDOWS

fruityloops

(my prefered choice its easy to use you cant save in the trial though)

cubase

(cubase is a professional tool in doing so it is quite complicated to learn to use the trial dossnt allow saving so it would be useful just for looking around in or maybe using for live performances)

reason

(reason i havent used very much it was confusing for me on first glance although many say it is better then fruityloops im yet to say that the cool thing about reason is you can plug virtual wires into different banks so it looks like you have your own mixing desk? cant remember the right term for it worth a look anyway keep in mind though you cant save like cubase and its 45mb )

noteworthy composer

(with this program you put notes on the measure the trial version is limited to a number of saves)

cakewalk sonar4

LINUX

rose garden

(boasts to be comparable to cubase on linux one im going to look at in the near future)

linux sound quality guide

linux sound guide

csound

planetccrma

ardour