I Have used this iso for my retail installs om 2 diferent machines. Both have booted flawlessly. I obtained my copy of the iso from the Hackintosh site forum. Same iso the one in this thread.

Boot the iso to the prompt - then eject iso
Replace w/ your purchased retail dvd and hit 9f then hit enter
The darwin boot will come up to either hit F8 or enter - hit enter
The dvd should then boot to the install screen
Install Leo - reboot
On reboot replace dvd w/ the DFE iso and boot as before - instead of replacing w/ dvd, boot from your new install. To do that, instead of 9f hit 80 or 81 (first disk install =80 - second disk=81)
Your new install should then boot.
After it boots, you need to install your kexts for your board etc..

My boards - GA EP43 DS3L and GA P35 DS3L - Both have a Q6600 By the way, these are great boards for os x86

scott