Check out the burning guide on Mod That Cube. Re the size, your image may work fine although the guide says 'An easy way to tell if your image is wiped is to check it's filesize. If the image isn't exactly "1,459,978,240 bytes" then it has been wiped, underdumped and/or curroupted. To fix the image with FSTFIX go to our downloads section, grab "Loony Cube's Wiped GCM Fixer/FSTFIX v1.5f", extract it to the directory that contains the image and then run it via the command line interface as shown in the example below.' I use x16 max full size DVD-Rs and find that they work best for burnt at x8 (burnt at x4 wouldn't boot at all for me).
