this about sums it up.
i use MovieFactory 3 at the moment. my needs are mainly analog capture from DishNetwork DVR and miniDV. my editing is light, with simple removal of scenes, commercials. and unwanted material. i will sometimes edit the chapter points, but not usually.
i'm curious about PowerDirector, but i'm not ready to fork up the clams. it looks to have a great feature set. i was not a big fan of WinDVD Creator. Video Studio is a much more enhanced version of MovieFactory. i haven't used it, but it may be the one i ultimately go with. all of the others that i've used have come with various hardware purchases, so the cost to evaluate them was nill.
read, ask, and evaluate! everyone has different editing needs, thus the variety of software available.