First of all, Knoppix is based on Debian, so you don't need to install most software via RPM. Debian's package management system is called apt-get and it's much easier to use than RPM. If you're not familiar with apt-get, it takes about a minute to explain.
Second, the password problem is easy to fix. Just boot from the Knoppix CD into runlevel 2 (type knoppix 2 at the boot prompt). Mount the partition where /etc is. Then edit /etc/passwd on that partition, deleting the "x" between two colons after "root" (probably the first line).
This will make your system monumentally insecure, but it will allow you to log in as root without a password. When you're done, reboot, log in as root and change the password with passwd.
Edit: You should also have a better root password. You may not be concerned about security now, but picking good passwords is an important habit to form. What I do is memorize a string of memorable gibberish and append a memorable word or pseudo-word to it depending on what the password is used for.
Whatever you do, don't post your root password on a forum like this. If someone were able to find your IP address, Bad Things would happen.