ATI Radeon 9000 Display problem

I have an old computer (Pentium III, 378MB) that I am trying to install Ubuntu 12.04 on. Using a ATI Radeon 9000 graphics card (PCI bus).

The LiveCD loads and runs. However, the display on the monitor only shows the top left quadrant (or so) of the full 'desktop'. Looks like the resolution is set to some high value (perhaps 1600x1200, I don't know) but the monitor seems to be set to mode with large pixel size (it that is possible). If it is possible to 'pan' (ie, scroll horizontally and vertically), the desktop may be usable. As it is now, I cannot even install Ubuntu on the computer.

Is there any way to get this to work?

Is there a way to run the gnome terminal in the 12-04 Ubiquity Desktop so as to run some commands?

For what it is worth, during loading, the display on the monitor seems to work correctly - the Ubuntu 12.04 logo is displayed centered in high resolution. So both the card and the monitor are capable working properly at high resolution.