In reply to dan bulman:
which version of windows? if win7 make sure you have the latest version of moviemaker. (i think it's moviemaker live 2011???)
if it's time to upgrade to something more functional then sony vegas gets good reviews on the "gopro" forum i look at and then if you are feeling flush (or isohunt naughty) the adobe premiere elements / pro is potentially the next step up again.
if it's not something you want to spend hours on hten the tips in the above posts and carry on what you're using are a good place to go... loads of tutorials on slide show and timelapse on youtube and others
enjoy