I recently booted knoppix 3.2 on a Dell Optiplex machine. Knoppix worked fine, but when I shut down and tried to restart I discovered that the computer was no longer working - It would not even get to the Bios setup, the screen stayed entirely blank and the diagnostic lights on the motherboard indicated it is a Bios problem. I had to get the motherboard replaced. I would STRONGLY recommend avoiding using Knoppix on a Dell Optiplex or any other Dell machines as it may affect them as well.