Perhaps you meant Meerkat - there is no mongoose. It's rather important
to get the details right, so the information I asked for is actually a
useful sanity check. The kernel version corresponds to 10.10, so that is
all clear now.

I asked for the output of lspci to find out what video hardware the OS
is seeing. But contrary to what you said earlier, there is no trace of
nvidia in the lspci output. Could you explain what you mean when you say
that the system thinks you have an nvidia card? What was the indication?

On all the systems I have with ATI cards, the built-in radeon driver
works like a charm, 3D effects and all - but for ATI cards that aren't
supported by the generic in-kernel drivers, you should be able to
install the ATI drivers without too much hassle.

Open the ubuntu software center and type ATI in the search box. I see 3
entries on my 10.10 desktop here and the 3rd one is called "ATI binary
X.Org driver/Optimized hardware acceleration of OpenGL with newer ATI
cards" and that's likely the one you'll want to install.

If you don't see the ATI binary driver, then go to edit->software
sources in the ubuntu software center and make sure all of the boxes are
checked. When that is done, the ATI drivers should show up in the search
results.