So I've been devoting myself to playing the hell out of Modern Warfare 2 and I still finding out which setups I like and which I don't. But I have a new found love of the Hardline perk. It's the one that gives you your kill streak one kill earlier. Which may not sound like much but it can make a big difference when your going for a freaking 9 kill streak.
For my first time I'm using the Scar with Slight of Hand and Scrambler. It's nice because even with losing the Stopping Power perk it can still drop people fairly well. Though sometimes then can get away when they shouldn't have. Anyway give it a try if you haven't and keep killing my friends. :)