You can but should not make any xbox iso with nero. If you do the iso's will be standard fileformat and not the xbox file system.
Use a program like Qwix or Craxtion to make proper xbox iso's.
The games that already are on your hdd will be fine doing iso off. FTP them and then make an iso and burn it.
There are also a good idea to take a look over at
xbox-scene and in their forums about gamedisc flie layout as it might be good for some games.
Hope that helps..
