I tried what you said. I saved and when I restarted same thing. Back to 640x480. It's also saying that I have a generic vesa card. I have been looking to find the answer, but to no avail. If anybody who set up Knoppix on a Tecra 8000 had this problem and found the fix, I once again ask for your help to fix it. Thank you.

20 minutes later: Nevermind. I finally figured out what the problem was. I was trying to use the wrong video drivers. Sorry for the inconvenience. The working combination is Neomagic NM2230 256AV+, for future reference. Thanks all.