A friend of mine bought the ECS K7SOM with onboard Duron, Sound and Network for under $80 - and he told me it works great (and fast enough for him) under Knoppix... out of the box... just insert RAM and CD drive and there you go... suoper cheapo!

For example (this is not advertising, you can buy this everywhere even cheaper) http://www.shentech.com/ecsk7v7amdpr.html