knoppix 3.8.1 (this is the newest, right?)
Right - very very new.

where can I find the source?
Good question. Not here: http://developer.linuxtag.net/knoppix/ - but it seems that this is where they're supposed to be. I found it by starting at http://knoppix.com/ then clicking on the link "Knoppix-Info," which takes you to www.knopper.net/knoppix-info/index-en.html and then clicking the link for "Sources for the special components of the KNOPPIX-CD."

I have a somewhat-new cheapo (emachines) desktop with an nVidia mobo. I was surprised - and very happy! - when Knoppix 3.7 detected everything just fine for me. (And so did 3.8.1. And so have Debian sarge RC2 and RC3.)

For my own curiosity, what's in your file /etc/sysconfig/xserver? Here's mine:
Code:
XSERVER="XFree86"
XMODULE="nv"
XDESC="nVidia Corporation|NV18 [GeForce4 MX - nForce GPU]"
I hope someone can give you better info than I have!

-- Ed