In short, it is possible to have more than one linux kernel on your linux partition. Therefore, you could load any of them...
I use grub adn it comes up on my boot. There used to be 2 enties, one for linux and one for dos (windows). Just lately I updated gaim and kernel and went into kde instead of Gnome. What are these two entries?
Red Hat Linux (2.4.20-31.9)
Red Hat Linux (2.4.20-8)