I just stuck an extra drive with Slack on it in my 510n. (Awful computers.) But it works great. Maybe try another distro. It might help if you took it step by step, too, like qwijibo was saying - what exactly did you do? Then maybe we could figure out what went wrong. Do you have one drive or two, did you install the loader on the mbr, etc. - do you have a 'hidden recovery partition' like me, which results in an error if you forget and tell LILO to boot Windows from hda1 so you have to go and edit lilo.conf to say hda2? *g* Stuff like that.
The fact that Knoppix won't load is very odd, but your CD-RW could be dying like mine is. Crap parts crammed into a micro-ATX case with ridiculously poor ventilation - everything in there overheats. I run it with the case open most of the time and just hope there's some useful parts in it when it croaks. I digress... Not sure what a 522 is like - hopefully better.