Can I Dual Boot Two Linux Distros on one hard driv.?

I know I can but can i just install Ubuntu after already having Fedora installed?
I am using Fedora 7 right now and i want to also dual boot Ubuntu 7.04 to try it. I’m D/l Ubuntu right now its a live cd but i want to dual boot so i can add things and use it like normal to try it and probably keep both anyway. I want to install to just one hard drive as my other hard drive is a usb hard drive I connect to my ps3 every now and then. Help is very appreciated as I’m a Linux newb