Just read this in the forums and I thought I’d try it out – it definitely worked, but just like everyone else who has done it, I’m way too excited to get a look at Halo 3, so I haven’t check out any of my other game saves.  Here’s what you do:

1. Go to your system blade in the Xbox main menu
2. Select Memory
3. Highlight Hard Drive and press Y
4. When the Hard Drive display screen is showing, press: X, X, Left Bumper, Right Bumper, X X
5. The System will prompt you, “Do you want to perform maintenance?”
6. Select Yes.
7. Load Crackdown – you will have lost updates so it will prompt you to apply new updates.
8. Apply the newly available Crackdown updates
9. Go to the Halo 3 Beta download screen and download it.

Again, I’m not sure what the “Perform Maintenance” does, so use it at your own risk.

See you on the Battlefield!