Beakybird & Lynn,
Thanks for your responses.
Lynn, I just downloaded Vanbasco's midi/karaoke player (version 2.52) and I can see that you can change keys while playing the file but it appears that you can't save the new settings with the file other than in the playlist. On the FAQ section of their website, it says that the original file can not be altered with this program and to use a sequencer like Jazz++. Maybe I'll give Jazz++ a try.
Thanks again for your help.
Nick