I have just installed the standard default desktop configuration of Ubuntu 12.10 (Quantal Quetzal). My PC only has 1GB of RAM and is struggling a little. What steps can I take to reduce the memory overhead of the standard install? If it makes a difference, I use Firefox, and a terminal most of the time.

Simply running those two applications I see:

free -m
            total       used       free     shared    buffers     cached

Mem:           938        873         64          0          5      167
-/+ buffers/cache:        701        237
Swap:          959        158        801

You can easily install and try out different desktop environments (instead of the default, Unity). Once installed, you can switch between different desktop environments at the log-in screen (there is an icon near your name, which, when clicked, allows you to select).enter image description here

Probably in your case, with 1GB ram, I would suggest the lubuntu desktop (based on LXDE). To install, open a terminal and type

sudo apt-get install lubuntu-desktop

If you don't want the whole environment, you can install LXDE by itself

sudo apt-get install lxde

Most everything will be the same but you'll have a new look that is less memory intensive (see many screenshots HERE). Firefox will be there, and the terminal will look a little different.

If you don't like the LXDE look, you can read about other desktop environments HERE. Options include Xfce (Xubuntu) and KDE (Kubuntu).


The web Browser

Firefox

Firefox is the default web browser of Ubuntu. It is a great browser but is not recommended for computers with minimal resources, since this has a large memory consumption. See Firefox working in my system:

firefox_mem_usage

Epiphany

I recommend to you the Epiphany Browser (now simply called as Web). You will be surprised at how well it works, it fulfills the promise to be lightly. The size of the download is only of 2Mb! As the Epiphany's homepage say: it is Simple, beautiful, and easy to use.

screenshoot

Others

In the Software Center you will find great Web Browsers that are lightly, faster, and smaller.