script/automator for exhibition

Hello,

first post. how exciting.

I'm struggling to get something together for an exhibition that opens next week.

in short, there will be a plasma screen attached to 13" mbp.
what I need to do is create a script/application that will switch from one application to another after a given time. it's not feasible for this to be done manually by a user (5 sites, over 5 days!)

eg
Launch Quicktime, Safari, Tweetdeck -->
run Quicktime movie once (fullscreen) -->
after movie (XX seconds) -->
switch to Safari (dynamic web page set as home) -->
after X minutes
switch to tweetdeck (displaying search results) -- >
after X minutes
repeat.

I've tried doing this in Automator, while it works for launching apps and movies, I can't figure out how to make it switch between apps.

any help will be gratefully received

Thanks!