Automatic resolution change when launching external player

Does anyone know of an application that will change my screen resolution automatically?

I've found command line utilities, etc. but I was looking for something that would automatically change my resolution when I launch totalmedia theatre to play blu rays.

I run my xbmc @ 720p ... anyway if not, I can write a batch file or something.

Just wondered if anyone know of a tool to do this on the fly.

Thanks!