Wikipedia, but I highly recommend playing it. I was in your shoes a year ago until I found MGS essential collection (1,2 and 3) and figured I'd buy it. I didn't like the whole idea of a stealth game I just wanted to play MGS4 because of the graphics hype behind it. But anyway I'm extremely glad I played it, it's in my top three best series by far, and the story is probably the most important thing about MGS, you have to play 1 2 and 3 to have the most epic experience with 4, and I mean EPIC, but you have to play the other three for it to be so great.
You could read the summaries and everything but it won't effect you emotionally at all, if you play the game it'll be like Hideo is playing with your emotions, you'll laugh, cry, get angry, feel sad, it's definitely an experience you can't miss out on. Especially MGS3.
