I use the command init # to change runlevels. If i boot Knoppix 3.6 from CD using the cheat code knoppix 2 vga=normal then I am dumped into a console session as root in runlevel 2. If after that I then want to run a normal KDE session I use init 5. If I want to reboot I use init 6 and if I want to shutdown I use init 0. Take a look at /etc/inittab as it will not only list the default runlevel but also list function of the other runlevels.
Here is a good page on runlevels http://www.telenovela-world.com/~spa...t-HOWTO-6.html.

I hope this helps.
James