Subwoff,
files with the .nrg extension are proprietary of Nero. I do not belive you can just rename the files from .nrg to .vob like you can rename a .vob to .mpeg or .mpg. I do know that you can use "daemon-tools" to mount .nrg files and then use DVDDecrypter to burn it just like an .iso.
Here is a link for daemon
[Link: daemon-tools.cc]Unfortunately, Macrovision Europe acquired the rights to the DVD decrypter software and forced most third party distributors to remove the freeware (including Afterdawn). I'm not sure where you can now get a copy, sorry :>( Perhaps a Google search will find it. I do know that a prog named MagicISO can handle .nrg files but this is a pay for prog. You can find MagicISO here:
[Link: magiciso.com]Good luck,
Erock