I have an ATI Mobility Radeon 4650 HD graphics card. And I have upgrated to Ubuntu 10.04
What drivers should I install for my graphics card?
First, be sure of your graphic card by checking in Terminal.
If the system shows you that
However, if the system supports the type of graphic system you use, for HD 4xxx / R700 based cards according to you stated, it can easily be installed using System => Administration => Hardware Drivers.
Restart xserver by logging out and back in, or typing
Check functionality by invoking glxgears.
Change overlay type to Xvideo if video upscaling looks blocky.