How-to site Tech-Recipes.com offers up a simple but helpful tip for changing a computer name after a Linux system is already installed. To make the change, open up a terminal and punch in the following:
gksudo gedit /etc/hostname
Type in your administrator password and you should get a file that contains the computer name. Change it, save it, done. I had to search this out myself when I organised my home network with a naming scheme, and some people may need to make the change if an office network requires certain names to log in. Note that while the article claims it's an "Ubuntu" tip, most Linux systems store the computer name in the same file.