I bought my Xbox 360 from the local Argos (strange choice I know). At the same time I also bought Oblivion as my very first high definition game. I remember just wandering around the countryside astounded at the detail, I must admit I quickly grew tired of the game itself, it just wasn't my sort of thing, but from a graphical standpoint, it seemed incredible. I came quite late to the high def scene, 2007, and I didnt have a high end computer so I had never seen this sort of thing before - good day.
Little irony was that my xbox was infact broken when I bought it, and would peculiarly ONLY play oblivion. When I bought Gears of War soon after, it wouldnt play it!