Without a doubt, Microsoft's Xbox 360 Games on Demand unveil at E3 gave gamers plenty of reason to celebrate. Just think -- no more camping out for midnight launches; you just fire up your console, make sure you've paid your internet bill and get to downloading. For those who just can't wait to see what said experience will actually look like on Redmond's console, the video just past the break does a commendable job of explaining. It looks as if the system logs your credit card information in order to make game purchases as easy as a few button presses, and games that are already on your HDD can be played while another downloads. It's good stuff, we