If portability doesn't matter and you don't have to record a live band to seperate tracks, go for the pc.
Nothing beats being able to drag and drop on screen and the hundreds of VST instruments and plugins available.
If you get cubase it comes with a drum machine, moog synth, reverbs etc.
Plus your not limited to 8 tracks or whatever. I've pushed mine up to 60 tracks with only 128mb ram. plus you can run unlimited midi tracks.