For future reference (ie, someone else with fat fingers!) the easiest way to reset the root password on your server is:
1. Boot from installation CD.
2. Follow the installation through until it starts asking you about disk partitioning (You don't want to go into this, otherwise you lose everything!)
3. Press ALT+F2 to get a console.
4. Mount the root partition (usually /dev/hda1)
mount /dev/hda1 /tmp
5. cd /tmp/etc
6. nano passwd
7. Remove the x on the line that starts root:x:0:0:
8. Save the file
9. Unmount /dev/hda1
10. Reboot without the CD.
The root password should now be blank. Once the server has booted, press ALT+F2 to get a console, login as root, press return for the password.
You can set a new password with the passwd command (this one will ask you twice!)
For remote access (ssh) to work, a password must be set.