How can I make a lnx boot CD that DOS can't read

[Steve F]

I am making a linux environment to use as a secure platform for online examination testing in classroom. My students will use their own H/W. I need to prohibit them from accessing their notes on harddrive, chatting with each other, or accessing the internet during the exam. I have setup a Morphix LiveCD. It boots to Firefox which is configured to only access the exam server. Everything is functioning correctly. At the beginning of the exam we hand out the CD's to the students. They boot their own laptops to the Linux OS, take the exam, shutdown and hand the CD back to the proctor. The only part I can't control is if after handing the CD to the student and before they boot it, they are able to copy the contents of the CD to their harddrive. This would allow them to inspect the system and its configuration at a later time in order to find ways to beat the system.

I want to create an iso and burn it to CD. When put it into a PC during startup, it should boot to linux and operate correctly. If put it into a PC running DOS or Windows it should not return a directory list. Basically to windows it should look like an empty disk.

Does anyone know how to do this? Or at least points in the right direction? Thanks,