Suggest you switch to the thread at:
Although the thread is about Red Hat and NTL, I use Mandrake 9.0 but the solutions still apply. If you do choose Mandrake, when it gets to the bit about your internet/network connection, you should specify "CDCether" from the list of network drivers. Probably the same for other distros.
Since you have cable, you can download Linux Mandrake or Red Hat for free (you also need CDRW to burn images to a disk and it is a very long download).
If you go into WHSmith they may have a Boxed Magazine called:
LINUX The complete guide. "Better Than Windows"
If costs £7.99, has the Mandrake 9 CDs inside, and the magazine is a beginner-friendly compilation of articles to help you with Linux.