First COD game?

First CoD I ever played was OG CoD on my old Dell Desktop Computer we had back then. Was really awesome even though I was pretty young.
I would say that the CoD that got me really playing on the other hand was CoD4 FOR SURE.
Got it the day of release back in 2007 for my xbox 360, didnt play any other games for a couple years other then some WaW and Halo3.
I still firmly believe it was the best of the series before the trend of mw2 clones flood the shelves every year.