Final Cut Pro is the way to go...

If you want to do some decent video editing, you can get by with a program like iMovie or the millions of other consumer-level programs available. However, if you really want to make some pro-level videos, you need to buy and learn Final Cut Pro. I use FCP 6, but they just released FCP 7, which has some nice updates/upgrades. You can see a review of the program here:

www.bhphotovideo.com/c/find/newsLetter/FinalCutPro-7.jsp