Debian 3.0r5 is about 3 years old & it is known as Woody and is considered Debian stable. This means that programs & packages only get updated with security fixes so all the packages work well but are quite old. Many of those distros you mentioned use the up to date 2.6.x branch of the Linux kernel as default. Debian 3.0r5 uses the 2.2.x branch as default and according to Debian package listsings, the latest 2.4 kernel is 2.4.18.

Knoppix 3.7 provides kernels 2.4.27 and 2.6.9 and Knoppix 3.8.x uses 2.6.11.x. Both the 2.4.x & 2.6.x branches have a kernel module called b44. Support for b44 was added to kernel 2.4 series in 2.4.22 as seen via the changelog here on line 240. The 2.6 series kernels also support b44 as seen in the 2.6.9 Changelog at line 27077. According to the changelogs, the 2.4 is getting backported fixes for the b44 driver via the work being done on the 2.6 kernel, so the Knoppix 2.6.x kernel should be more reliable.

In order to get support for your NIC you need to use the 2.4.22 or higher OR 2.6.0 or higher. In order to get the latest support for usb2/firewire/sata etc you should probably be aiming to use the 2.6.x kernel branch but that is not an option in Debian 3.0r5. The Debian group is working on a new release of Debian 3.1 called Sarge and it is expected in about a month. It will include the 2.6.8 kernel and it too has the b44 driver. If you do not wish to wait a month, then you can choose to manually compile & install a new kernel. You can find directions in the links that tdjokic provided.

I hope this helps.
James