We should crucify you upside down for defining the long cut scenes as "boring" lol
Just like Strike911 said, the whole story is in the cut scenes. As you said, they're usually quite long, true, but if you are actually a fan of the MGS story, you'll be looking forward to these.
That's why you should start with MGS1, either on PS or on Gamecube, get intrigued by the whole plot, it's just amazing! Or else, if you really don't care about the story or lack the patience of watching, just play directly MGS4. But you'll get only a few percent of the whole fun, and that will really be too bad.
Anyways... whatever you do, enjoy