I don't know about the nivedea... But I just went through the process of
installing the ATI Radeon driver. Step 1 was to get a driver install
script from the ati site (the open source driver in Ubuntu repository down
not work well with accelleration). This script builds 3 deb packages that
will install the driver.

Mine didn't work quite right, but I realized this morning I probably have
the "HD" card version, even though lspci does not report the hd part. I'm
trying again tonight. I can point at the site and installation instructions
when I'm back off mobile if you want...