You should be able to do a PoorMan Install on the 750M HD. Procedure is to boot 'knoppix toHD=/dev/hd(whatever knoppix calls your new HD--should be hdb I think)" & see if it will go. You can then (in fact you can do it now running from the CD) set up a persistent home on your 'main' HD. See the docs in the navigation bar above; there is a How To on persistent home, poormans install and also see 'Remastering from a HD Install' which has some info on a poormans install.
You will get a more complete system from the Knoppix poormans than from Damn Small or other small Linux distros simply because Knoppix is a complete system with a lot of apps built in but compressed whereas the others are stripped down uncompressed systems.