There are two easy to use tools for converting NRG (a file format used for CD images by the Nero Burning ROM application) to ISO: nrg2iso and iat.
To install them on Ubuntu, type:
sudo apt-get install nrg2iso iat
Use nrg2iso like this:
nrg2iso cd_image.nrg cd_image.iso
And for iat:
iat cd_image.nrg cd_image.iso
iat supports many CD file formats, including ISO, NRG, BIN and MDF.
Updated: Sep 14, 2008