I've yet to download it - I'm scared at the thought though... full of screaming 8-year-olds no doubt.

Theres no way for you to get it unless you have the Crackdown disc - go and rent it though. Keep in mind that you need the disc to play the beta.

On a side note... MS have now started banning modded xbox 360s from Live. Hopefully that'll get rid of some of the aforementioned 8-year-olds!