Well it depends on what you are planning to do to your vids. If you want the standard point and shoot with text here and there you can use Windows Movie Maker or for Mac: Imovie. If you are making something fancy then I suggest Windows: Adobe premiere or maybe Sony Vegas for Mac: Final Cut Express/ Pro
I use vegas movie studio, its awesome. I use the smaller version which is a bit over $100 as apposed to the full $600 one. Unless you go into some really serious video editing, the smaller version will suffice.