I'm no expert, but I think there are several ways to fix the problems without re-installing. Since the video is messed up, hit ctrl+alt+F1 to get to a text prompt. Try the command "hwsetup" since this is the program that Knoppix uses to autoconfigure everything on the CD. After it is finished, hit ctrl+alt+F5 (the F5 is for runlevel 5 where I think KDE is at, if that doesn't bring you back to your messed up kde screen, try different function keys, maybe F7?) then ctrl+alt+backspace to restart X and kde.

I think the above may work. If not, you can try to go back to runlevel 1 (ctrl+alt+F1) and enter the command "kudzu" to detect hardware, then try "hwsetup" again. Go back to runlevel 5 and restart X with ctrl+alt+backspace.

If all else fails, reboot the computer with the Knoppix CD. It you have a working display with the new monitor and video card, just copy the working configuration to you hard drive. To do that, as root type:

mount /dev/hda1 /mnt/hda1

This assumes that your Knoppix install is on hda1, if not, enter the place where it is installed. Also, the Knopppix CD should automatically create the directory /mnt/hda1, if not, you can create one using "mkdir /mnt/hda1". After you have mounted the Knoppix partition that is on the hard drive, back up the existing configuration:

mv /mnt/hda1/etc/X11/XF86Config-4 /mnt/hda1/etc/X11/XF86Config-4.old

Then copy the configuration from the CD:

cp /etc/X11/XF86Config-4 /mnt/hda1/etc/X11/XF86Config-4

And you should have the display working as it does from the CD when you reboot. When you take your computer back to your own monitor, you can use the backup copy using "mv /etc/X11/XF86Config-4.old /etc/X11?Xf86Config-4"

Good Luck!