I've tried to install and encourage various people to use knoppix, or other linux distros.

The modem, internet access, is usually where I have to give them Windows back.

Having moved from New York to Sao Paulo, in Brazil, I'm having this problem much more often, as people here have very old computers, with cheap modems.

Lightweight Linux with modem drivers is what they need, but there's no such distribution.

Buying another modem, waiting for it to be installed, visiting linmodem.org and recompiling the kernel, suggesting DSL, etc is just a prelude until someone says "forget it.. let's just install windows".