hi
Dual boot is not a problem with knoppix in my experience. Llilo takes care of the job. No problems booting into linux or windows. I have installed a dual boot on 4 different computers including a laptop. Each computer had only one hard drive. They all needed their different cheat codes to make them happy...

I just did a "debian" style hard drive install(knoppix-installer) with an apt-get dist-upgrade after booting the computer. The full upgraded install was 2.7 gigs. This dosn't include the swap partition(usually twice your ram). I also run the knoppix-terminalopenmosixserver from the hard drive. Which at this point means copying the knoppix cd to the hard drive. You would also need to include space for all your own files(music, work, additional programs, ect).
johnb