I use Kanotix Linux. It's a Knoppix derived distribution compiled for later generations of Intel processors (i686 & later) & other hardware. Kanotix is more amenable to HD installations than Knoppix. It has even managed to get my laptop's winmodem working, something most other distributions I've tried failed to do.
Knoppix, in turn is a Debian based distribution optimised for running from a CD-Rom (ie it doesn't need to be installed to a HD) with renowned hardware detection.