You have to have *some* driver set and if its detecting that you have a given
chip and then you remove the driver for that chip it's not going to work.
It's being auto-detected on the fly in modern distributions.
If there was another driver available in 6 and its been removed from the
distribution then your not going to be able to go back to it. If it still
exists then check the xorg config file in the prior version which did work.
But, as everything is auto-detected on the fly in modern distributions that
won't quite work either. I think there is some way to have it create the xorg
config file for you though and then it'll probably work. Find those
directions, run them, and see what driver is being used in 6. Then do the
same for 7 and change the driver to whatever it was in 6.
That said I'm pretty sure this is all going to be a wasted effort..
