Ubuntu can be installed using other methods as well, which might prove handy in some circumstances. For example, let's say you want to install Ubuntu on a computer that has no CD/DVD-ROM drive. What do you do? Well, you can install Ubuntu from another machine on the network (if there is one) that will provide the installation files to other computers on the LAN, or you can install it from the hard drive if there is no LAN. For the latter solution, you will need an active Internet connection to download the Ubuntu ISO image or you can use an external hard drive as well.
I have recently started expanding my research based from previous tutorials on network based installations and PXE booting + network based installations to include automated Ubuntu installations. I will mention that I do not consider myself an expert at this by any means, but I wanted to give some of you a preview of what will end up being a much more mature tool.
Now, the Ubuntu 7.04 that Dell ships with their systems, is available to download.