I'll start you off with a few links....You guys are ganging up on pressing all my buttons!
I can get started on this one... but I'll let someone else have a go for a change.
Margarine vs butter. Marks... Set... Go!
http://www.nytimes.com/1994/05/16/us/fat-in-margarine-is-tied-to-heart-problems.html
http://wewantorganicfood.com/2007/09/12/butter-versus-margarine-are-they-good-for-you/
http://www.wisegeek.com/what-health-problems-are-associated-with-margarine.htm
http://steveshealthanswers.com/health-news/should-you-eat-margarine
http://www.whale.to/a/roubos.html
http://www.healthy-eating-politics.com/margarine.html
http://www.stop-trans-fat.com/margarine.html
http://www.godlikeproductions.com/forum1/message673196/pg1
That should be enough for now!