you need to manually change the default kernel in grub.
Go into a term window (or a command prompt if you booted there), and type:
vi /etc/grub.conf
inside of grub.conf, there is a line that says
default=1
change it to
default=0
EDIT: I forgot to say, if you're really really new to linux and have never used vi, you have to press the insert button before you start editing, and when you're done you have to press <esc>, then :wq to save and quit. If you knew this, sorry for being patronizing, if you didn't, learn to use vi, it will be your best friend.
