Can you see the files on the original CD that the Evo X came on?
A program called xISO will read an xbox disk and convert it so it can be read in both the PC and the Xbox. It will also burn a 100% compliant image for you as well. You can find it here (it's freeware):
http://www.yursoft.cjb.net/
The site isn't in english but you should be able to work it out. Click where it says "XBOX" on the top right and that will take you to the download page.