I don't have a car, but I actually made a program that did this.

I then found a more stable, more efficient, more reliable and functional one.

I found [="http://www.sunderlandclc.org.uk/index.php?option=com_remository&Itemid=86&func=startdown&id=25"]this app[/]="http://www.sunderla…"]this app[/] with a short search but I can't find the much nicer looking one I had.

Alternatively, I'd use [[url=http://="http://www.foobar20…"]foobar2000[/]="http://www.foobar20…"]foobar2000[/], set it to Stop After Current (check the Preferences-General tab - there's a "Reset stop-after-current when stopping" and I can't remember the default), then load all your stuff in that.
Foobar2000 for me, has been rock solid, and will play damn near anything (including audio formats used in games).

Thanks codemonkey! I don't think that Fubar200 will work, as we will probably need to have more than one sound running at the same time. In other words, I'll cue a "bed" track, then at certain dialogue cues in the play, trigger additional sound effects and such. I'll play with that other one, though! Andy

I'm starting to think I'll dig out that old program of mine...

I had it rigged to provide 9 keyboard/mouse activated channels (independent) with volume controls, and even a coloured version of the script.
It was hack upon hack upon hack, but only ever crashed once besides testing.
Now, where did I leave the source code...

Thanks for your input! I've found something called Mixere which will do what I need for this show. We'll be putting it together in tech rehearsals next week! Andy