Most of the 12.x drivers will with with a 7xxx and a 5xxx card.  I had 12.4 humming along, but it gave me problems overclocking...  I'm now on 12.8 (and the associated SDK) and it seems to work fine.  If you down-grade the drivers, make darn sure you kill all the orphaned ati* files in the System32 and 64WOW directories or it will be a waste of time. Make sure when you install the drivers it shows that the video driver needs to be updated (do a custom install where you can see the individual components being installed). If it says it is already up to date (or newer) then you have left the old ATI files behind and they won't be down-graded.

You can use GPU-Z to get current driver versions on your rig if you are not sure what is currently installed\used.