Removing vocals

Anybody have a good tip on how to remove vocals in Garage Band?
I'm not talking about a song that I've created but an imported tune.
Think Karaoke.

I doubt it is possible to do in Garageband...

The normal method requires that you run the stereo tracks split and parallel to each other but invert the phase on one of the channels (left or right). What happens is that since usually the only sound that is equally panned left and right is the main vocals... the inverted channel's vocal track will cancel the remaining track's vocals out. That being said this method is very depended on the method by which the track was mixed originally... Some CDs work... others will not.

In SoundTrack Pro i believe you can use the Process/Invert tool to invert audio phase of one track. Cooledit, Protools and Adobe Audition have similar functions also... But I don't believe Garageband has this ability... Nor the ability to split a stereo track into two seperate mono tracks.

I wasn't sure but I thought not.
Thanks anyway.

I am pretty sure you can do it in Audacity (which is free).