I played Adventure Island II on NES before I saw Wonder Boy on the Game Gear in the early 90s. It immediately struck me how close these two games were, but since I was a child back then I didn't really cared. Years later I learned about the connection of these two series, must have been in the dedicated Game Sack episode I think.
I managed to beat the Adventure Island II port on the GameBoy (not sure if it was titled the same), but haven't finished the NES one yet. I've seen Monster World 4 (that one with the green haired girl, please excuse me if I got the name wrong) several times, and I wonder if I should give it a try on the Xbox 360. The graphics look so nice.