Need help with installation of ubuntu 8.04?

I'm a new linux user meaning i have only navigated servers with linux and have never used it on my PC. With the advent of windows Vista and Windows 7 Microsoft has now become dead to me. Anyways, i have been waiting for about a half hour now and my installation is not complete the only prompt i have received so far is the initial install prompt. Since then the screen has gone black and come up with a background image and then repeated this process. My computer is not frozen because the HDD and Cd-rom lights are going. How long does an install take, i am running what some might consider outdated hardware 256 MB RAM and Intel celeron M processor (not sure of the speed) to be honest this computer is not my first choice but considering lack of money it will have to do. Anyway it might be important to note that i burned the iso to a dvd-r 16X disc. Is that why it might be taking so long? How long does it usally take?