I helped you identify the problem with your network card. It is made by Microsoft and is tweaked by MS to not work with Linux. If you want this to work from the Knoppix CD then you should replace your network card with a one that works with Linux.

3Com 3c905b-tx will work with Linux & windows with no tweaking necessary. You can get it shipped to your house in most cases under $15.
http://www.pricegrabber.com/search_g...rch=3C905B-TX/

Or you can go to a local computer/office suppply store and buy a network card & try it out in the PC. If you don't like it or if it doesn't work, you can bring it back & get another one.