I hope this will be to some help for you ( I found it on : http://www.gentoo.org/doc/en/handboo...?part=1&chap=2
To burn the downloaded ISO(s), you have to select raw-burning. How you do this is highly program-dependent. We will discuss a couple of popular tools on how to do this.
* With EasyCD Creator you select File, Record CD from CD image. Then you change the Files of type to ISO image file. Then locate the ISO file and click Open. When you click on Start recording the ISO image will be burned correctly onto the CD-R.
* With Nero Burning ROM, select File, Burn CD image. Set the type of file to *.* and select the ISO file. Older versions of Nero will tell you they don't recognize the format -- confirm here, it does recognize it but doesn't know it yet
In the next dialog, set the following parameters:
o Type of image: Data Mode 1
o Block size: 2048 bytes
o File precursor and length of the image trailer: 0 bytes
o Scrambled: no
o Swapped: no
Now click on OK and then Burn (the CD-R)
* With cdrecord, you simply type cdrecord dev=/dev/hdc (replace /dev/hdc with your CD-RW drive's device path) followed by the path to the ISO file