I'll pretend to be Sir.. (just image me with a cool British accent)
If your really looking for professional, I would recommend Adobe Premiere. very nice, easy to use as well as very in depth & complicated if you really get into it. Lots of options Of course you'd prob have to get a hacked version or something cause its way over priced (just like every other Adobe product)
but yeah- everything else sucks compared to that. (excpept iMovie If you have a Mac
)
oh there's also 'Virtual Dub' which is totally free and very good, but its very complicated to use. Lots of people said they liked it but I've never been able to use it well. I always have to download a million codecs and it crashed a lot for me. But if you can get it to work its good. It is useful for getting still frames from videos