Ubuntu CD Doesn't Even Boot

I downloaded Ubuntu and burned it to a cd using Nero. My Dad also did the same thing on a seperate cd. We changed the BIOS so that my laptop will check the D drive before the hard drive and boot up windows. I'm trying to partition my hard drive to use both windows xp and ubuntu 7.04. I tried using both cd's and first it checks the D drive and I can hear it working and all, but then after a pause, nothing happens and it goes straight to boot up Windows. I've checked forums and blogs and step-by-step installation blogs but what they said is supposed to happen ("Wait a few seconds and you will see a window on your screen called Ubuntu 7.04 (Disc Tree). If you click where it says "Boot from this CD to try Ubuntu without affecting your system." you will see a page with screenshots and information about Ubuntu Linux. From this page, you will learn that in order to boot from this CD you must close all your running applications and reboot the PC.") doesn't even appear. Is there any way to check how successful my download/burning process was? Is this a problem with how we burned the CDs? I requested a CD in the mail, but I'd really like to get Ubuntu installed asap. Any help is much appreciated!