I am a complete new user trying to set up Ubuntu on an old desktop. It has an AGP Radeon 9550 graphics card. I am running Ubuntu from a USB drive with persistence as the PC currently has no hard drive

I seem to be stuck in 640*480 mode. The desktop itself is larger, but the monitor display is stuck on 640*480.

In Settings>>Displays, only the 640*480 option is available.

What I have found out so far:

• The proprietary ati drivers no longer support my card.
• If 3D isn't an issue (it's not) the open source driver should be fine. This should be installed by default so in theory I am using it already
• xserver-xconf/pci/*.ids doesn't show any entries for the card's PCI id.
• hardware additional drivers show no proprietary drivers

I tried the booting into the current version of Geexbox from a USB stick and this set the resolution correctly by default so I know it can be done, but I know no idea how.

How can I tell what driver the card is using, and how can I get the higher resolutions back?