I just got a 750GB Hard Drive. I would like to use it for Time Machine but I really don't want to use the whole drive. In fact I really don't want any more than a weeks back up. Time Machine doesn't really seem to have too many options. Is there any way I can set it up to where it only backs up the last 7 days? For what I do I would never need anything more than an image of my disk and 7 days of info. Any help would be great. Thanks.