Look into the Sony Vegas line... a pretty decent software can be bought for less than $50 and is MUCH MUCH easier to use than movie maker. It's more stable and will allow you to put together quick clips. I use Sony Vegas on my windows laptop and iMovie on my Mac. Most of my salmon videos are done on my laptop since I do them up at the lake. I used to do them on moviemaker, but it got too time consuming. I think I got my software off amazon for like $25 or so.
Nick