I downloaded and installed Kubuntu Linux on my (4 year old HP) laptop. So far I like it except for the fact that I had to install Firefox myself. After some googling, I discovered that Kubuntu does not include Firefox by default.
Being a Windows user my whole life, I am not used to having to do a lot of research on installing an application. Eventually, I found this site which points to this script that an Ubuntu forum member (named aysiu) initially developed and was later modified by nanotube, that will download and install the latest and greatest version of Firefox for you. Review this thread.