What is the best software going around that will cut vocals out of an audio file like WAV or MP3?

I want to be able to chop some vocals out of a few songs and sample them into my Motif XF or even Sonar on my PC for use over some of my custom sequences.

A lot of the official Yamaha Motif Demos with Bert Smorenberg use samples from Madonna / Michael Jackson etc and they sound perfect. is this something only Yamaha can get their hands on because they are Yamaha or is it something anyone can do in their own home with the right tools?

Thanks

Nick