Title says it all, this is a ripped demo from the new Tony Hawk's, so no need to rent/buy that to try out the demo. Found this info over here
XBox Live the Guide :: View topic - Guitar Hero 3 demo now available
1. Download the gh3.iso file from
MEGAUPLOAD - The leading online storage and file delivery service. (Top right corner of that page type in the 3 verification letters and click download, for those that don't see it right away =p).
2. Burn that .iso file via something that burns .iso files, duh. I used Nero (I think you need to use a DVD disc also), but i hear you can use
The Official ImgBurn Website also which is free, i think - havn't checked.
3. Put the disc into your 360, and go over to the "Games" blade and you will find the demo accessible under "Demos and More" (no you cannot start it up clicking play game). Tada, you can now play the new gh3 demo which is typically only available on the new Tony Hawk game.
There's 5 songs on the demo, including Tenacious D, Scorpions, and Priestess, Pearl Jam, and Pat Benatar. After playing this, i cannot wait another 9 days for the official release, it's going to be awesome. Have fun!