I can tell you this, I've got a similar system (133, 48MB RAM). Knoppix is going to be SLOW!!! You may want to go investigate Damn Small Linux http://www.damnsmalllinux.org/ or as recently recommended to me Flonix http://www.flonix.com/ I've not as of yet used Flonix so I can't say too much about it. DSL is pretty cool though not as cool as Knoppix

Just for the record, though, your BIOS (sometimes erroneously referred to as CMOS) is not part of the OS. It's part of the motherboard. The BIOS is usually accessed by pressing F1, F2, or DEL. It's different between manufacturers. You can usually change your boot order somewhere in there. But again, I've a similar system and it won't allow the CD ROM as a boot device. You'll have to make a boot floppy.

I think, if memory serves, there's a program you use from Windows called rawrite2.exe and a boot.img in the /KNOPPIX folder on the CD. I didn't make my boot floppy that way as I used another PC booted to Knoppix. I think, and I'm guessing here, if you copy both items to a folder, navigate to that folder from a command prompt, and do "rawrite2 boot.img a:" without the quotes it should work. I could be mistaken though.

Lemme know how it goes,
'Goon