We won an x box for free a few years ago, we also have a gamecube (which they don't really play)
My soon to be 10 year old likes the Xbox better.
He has tons of sport games, like Amped, Tony Hawk, and some other ones. He also likes Starwars games.
My 9 year old likes the Gamecube ok, but its sort of limited to what he likes. He says some Gamecube games are "baby" games.
Mind you, we don't have M games here. We do allow some T rated games depending on the game. For example, the Star Wars game is T, but its the sci fi animated violence that doesnt bother me.
Yes, the Xbox game can become a DVd player if you buy a special remote.