Quote Originally Posted by Harry Kuhman
If you're comparing Knoppix and Debian then you are apparently thinking of installing a system to hard disk. See answer #2 for a pointer to the faq that explains why installing Knoppix is not a good idea..
I couldn't find the answer #2 you were referring to, but I assume you're talking about the security remarks in the Knoppix FAQ? I don't recall reading anything about why installing to HD was inherently insecure since it is supposed to be some sort of Debian install, but I can well understand that security of the HD install in not a priority for Knoppix developers.
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Debian does have the problem of being an extremely slow to change system. If your computer is from the last century then Sarge/Stable might run on it well, but stable is too old for my liking. At the moment I use Etch and would suggest Etch for anyone considering Debian unless they want to be on the bleeding edge. In spite of the term "testing" I find it very stable. Etch was due to become the stable version last year, but as already said the Debian group is slow and an internal fude is delaying things further. I expect when there is a new testing I'll switch to that.
Does Etch get security updates via apt? I'm unclear about whether the testing security group does this. For the most part Sarge is fine for me, but I would like to use a later KDE and still get security updates.

There are a lot of Linux distros out there and you really have to pick your own. Some like Ubuntu; I con't see any merit to it, but maybe others find hardware support missing in Debian. It does seem to have a faster development cycle, if that's what you're looking for.
Apart from supporting my linmodem out of the box, I liked Ubuntu for similar reasons I like Knoppix - more up to date than Sarge and it looks like someone is adding an extra level of quality control/refinement to the standard release, however I'm uncomfortable with having a for-profit corporation behind the distribution which appears to diverge significantly more from Debian than Knoppix.

The stand-out reason to use Knoppix is obviously its portability. I'm curious how well this works in practise and what percentage of Internet cafes are happy to let you boot up your own O/S.