Music and video works 'cos its delivered in a set stream.... games are essentially random access. so the buffer therefore has to be the complete game, not just the next/previous six mins of video.
I'd like to able to stream games, but most things trasfer in a few minutes anway. or try project 411. im sure ive seen some places that sell 'empty' cases so you can house the new hdd easily. im sure that a clever person could set it so that all hdd turned 'off' in relation to the xbox, are 'on' in relation to your raided pc.
f*ck that for a challenge though