Are you talking about your hostname?
localhost is the default entry for the loopback address.

if you are talking about this:
You can change this using the 'hostname' command:

Then change your network config file to specify your new hostname.

In Redhat this is typically located in:

This worked. My terminal now says:
[alex@new alex]$ []

I know I can replace "new" with whatever I want.

Now, for the network file. I can't modify this in gedit and save it. It is readonly. Is there a way to change this?

The only reason it's readonly is because it's in the /etc branch of your filetree, which requires admin privaleges to do anything in there. In fact, almost anywhere other than your home folder on a *nix filesystem requires root privalges. So, you'll need to open Gedit like this on a command line:
Now do your editing and try to save. It should work.

yes, some systems dont have SU by the way (namely ubuntu) so use sudo and enter YOUR USER password in that case

Actually, I'm pretty sure that Ubuntu does have su. It's standard with almost all Linux distros. The problem however, is that although Ubuntu does have su, it's rendered almost useless as the root account is disabled by default.

You can still use it by entering sudo su at the command prompt, and additionally using passwd to change the root password, enabling the root account. </useless tidbit of information>

I believe it does have 'su' however by default doesn't put anyone in the proper group to use it, therefor, makes it almost unusable. (without detailed linux knowledge)

i think you need to be in wheel group

speaking of ubuntu has anyone got it installed on a thinkpad?
Ive filed kernel bugs since hoary and no solution