Hi Ray, > I do have Nero, but the thing I can't quite get my head around is, what exactly makes a CD 'bootable' with the appropriate ISO file being burnt to it. The ISO file is a special format single file which, when extracted and written to a CD, will become whatever the creator of the file intended. It's a bit like a zip folder, but there are obviously differences. For example, some ISO files contain an "autorun.exe" file, and this is what makes then run when you put them in the CD drive. I would imagine that the ISO itself will create the bootable function in much the same way. With Nero, you simply open the .ISO file, and then burn it. George.