I have downloaded a copy of Knoppix C'T 3.4 from someone's webserver (slow) and booted it on my Dell 5150 laptop with just the following at the boot prompt:
knoppix26 lang=en
(didn't need "nosmp" this time! but you do need to use shift-0 to get the equal sign because its a german keyboard layout at the bootprompt)
Anyway it booted up fine, recognized the broadcom nic, radeon ati card, the sound card and the USB ports!
As "windows_no_thanks" was saying, it may be because i have the latest version of the dell bios (A31) on my laptop. Be sure to get it from the dell support download page.

Moustache