How do i burn an iso with disk utility?
Rename it to a .dmg
If you're downloading ML now, open the applications folder after it downloads, right click and show package contents. Go to the contents folder and then shared support folder. Drag the InstallESD.dmg file to the disk utility sidebar and select burn.
You do need dual layer DVDs though. I've been told there's not enough space on my standard discs. Have to go up to tescos later and get some.