in my humble opinion, knoppix should boot by default in a resolution not larger than 800x600 (both in console and in X).
I know it's possible to change it at bootup in case it's not working on old computers, but it's difficult to tell newbies (you want to convince to use Linux) to do this themselves, especially when you have to deal with framebuffer options, x resolutions and such. On some old computers I had to test 3-4 times different options to make them start the x server correctly, and the 1st problems already appeared because of the 1024x768 console mode...