I also think this is valuable information !! I would like to use Knoppix in my organisation, but have no clue when I buy hardware if it will work.

Maybe on KNOPPIX.NET a database can be installed, where users can report if hardware is compatible ? A very small database will suffice.

Type: mainboard, cpu, graphics card, ...
Brand: Nvidia, ATI, AMD, Intel, Asus, ...
Type: Geforce 4 MX 440, ...
Knoppix version: 3.1, 3.2, ...
Compatible: yes / no

The rate of compatibility can then be calculated by then number of Yes/No answers. So if 20 persons report a piece of hardware as Yes (compatible) it will have a 100% compatibility rate. If 15 report Yes and 5 No, it will have 75% compatibility rate.
This way you can easily search the database and get an idea of how many users already used the hardware and their success rate.

Hopefully this idea makes it !!
Erik.