Radeon HD 2000, 3000, 4000 on Ubuntu 12.04.2 and higher: fglrx (legacy) unsupported, what to do?

If using AMD/ATI GPU drivers: Run the following command to remove them, and reboot:

sudo apt-get purge fglrx

Don't reinstall them as ATI cards (rather AMD Catalyst) currently don't support Unity-3D.

As to the optionsyou have, I'd suggest #1: Wait for AMD/ATI to catch up.

I have ATI Mobility 4650 HD and installing from Tomasz Makarewicz's AMD Catalyst Legacy PPA broke my unity and opengl. I got things working with this (found in the 2012 ubuntu forums thread Can't install ATI proprietary drivers in 12.10. Unity is Missing):

sudo sh /usr/share/ati/fglrx-uninstall.sh
sudo apt-get remove --purge fglrx fglrx_* fglrx-amdcccle* fglrx-dev*

sudo rm /etc/X11/xorg.conf

sudo apt-get install --reinstall xserver-xorg-core libgl1-mesa-glx libgl1-mesa-dri libgl1-mesa-glx libgl1-mesa-dri
sudo dpkg-reconfigure xserver-xorg

sudo reboot

I hope this helps until there is an official driver release by ATI.