You don't require Disk 4 in your optical drive if you use the "No CD Crack". There are two different ones around the file libraries for FS9: One is for the sim without the update, the other one for the sim with the update i.e. FS9.1. It's a good idea to use the correct one. I'm pretty sure both are available here at Flyaway besides other places - I just can never find anything here. I'm sure Flyaway or Radarman will give you the link if you get stuck.
Should you have scruples regarding the crack, ...don't. The successor to FS9, FSX does not require a disk in the drive to be run. Obviously Microsoft realised that the requirement of inserting a disk into a drive could not prevent piracy. Makes you wonder, I always assumed that those guys at MS were all geeks
Oh yes, this crack is merely a modified .exe file which, once replaced with the original will fire up the sim without the need for disk 4.
I didn't think one could make copies of this kind with Nero. I'd suggest you make .ISO images instead. If you're unfamiliar with the .ISO format, it is simply an EXACT image of the original. There are many payware programs that promise all kinds of things in relation to .ISO. I have been using
ImgBurn for some time now. It's free and excellent. Just google for it and make sure you check out the GUIDES which are a section of their forums.
You might also need Daemon Tools. The Lite version is free and excellent.