Is the O.C. over? How did it end?!

Is the O.C. over? How did it end?

I'm starting to get hooked on the OC reruns of SoapNet. There in the third season right now and I know Marissa dies. Is that the final season or is there another? Is it an ongoing series?

How did it end? Seth's parents have another child, a girl. Summer and Seth get married. Ryan becomes an architect. He gets close to that one girl, I forget what her name is. She's really annoying and nerdy and hangs out with Summer all the time. Julie is about to marry a weird businessman, but in the end I'm pretty sure that she hooks up with Ryan's estranged father.