there are many progs that can do simple editing. it only depends on what you expect from your video.
windows movie maker is sufficient enough, but if you want more advance(fancy) effects you'll need a better video editing software. personally I like 'premiere pro 2' and 'avid xpress', but they cost a lot of money. on the other hand there is 'sony vegas 6' which many beginners prefer.
if you want some really cool effects you'll need to get programs like 'after effects', but learning those will take you a big chunk of time. good luck