NRG file recognised as ISO9660 but not really recognised

I have a couple of files with .nrg extension ripped from dvds. I believe they are not corrupted.
I try to convert them to iso (I don’t have softwares able to burn nrgs in my Mac), but nrg2iso says the file is already an iso9660 image.
I rename the file as .iso but DiskMounter (system helper to mount image files under Mac OS X) is not able to mount it, the image is not recognised. DiskMounter is able to mount images if they contain udf, iso9660, hfs filesystems (maybe more).
Since Burn and other burning utilities use the operating system framework for burning, I cannot burn the image directly (is difficult to compile cdrecord by hand).
I own Dragonburn also, so I tried it. It is able to see data inside the nrg file, but then it locks, somehow, during the burning to a standard iso file. I tried to burn on a blank media but it locks in the same way.

Now, how could I burn them? my problem is that I cannot place them in a fat32 partition because of the size (>4 gb), and I cannot read them with my Nero Essentials inside my VirtualPC machine, because the virtual machine has win2k and is connected to the Mac host via smb, that has the same limitations as fat32 volumes.

Any help will be appreciated.

If you have a working Windows 2000 on a virtual machine, maybe you can install ImgBurn on the virtual machine and use it to burn the NRG file.

The only problem is finding a way to read the images with the win2k virtual machine: when I browse the virtual network, the nrg images appear as 200 and 300 mb files… the first 4 gb seem discarded.

The cause of the 4 GB limit is the filesystem I used in the VPC image: FAT32.

But that’s not a problem anymore.
The internal hard disk died. Again. Next installation of win2k will be on NTFS.