I did a HD install of Knoppix 3.4. When I boot I see a graphical Debian boot menu with a choice of Linux, Linux 2.4 and Linux 2.6. So far I've just let it go with the Linux default. What's the difference between the 3 choices (2.4 and 2.6 referring to different kernel versions maybe?) and what's the impact of choosing one over the other?