The Xbox uses a file system called XDFS, and if your disc is not compiled correctly it simply will not boot. The best tool for the job is [link] Qwix. Its the fastest and most compatible homebrew tool we've ever used for this job. Here is a quick and simple tutorial on how to create an XDFS iso from a dir of files.

Open Qwix



Click on the browse icon to locate the DIR where the files for which you wish to create a disc.



In this case they are in a folder called "xbox" on the desktop. Select the folder and click OK.
YOU CAN INSERT A DISC INTO YOUR XBOX AND JUST SELECT FTP LOCATION AND POINT IT TO YOUR D:/ DRIVE


Now click on Create ISO



Select the destination for your ISO image. Here, we have selected the desktop again and will call it xbox.iso. Click the Save button.




Then burn it.
for "M"
http://www.xboxisozone.com/community/forums/2/introduce-yourself/66/