While this is not an ideal fix at least we can play it without worrying about having a seizure.
http://support.amd.com/us/gpudownload/windows/previous/11/Pages/radeon.aspx?os=Windows%20Vista%20-%2064-Bit%20Edition&rev=11.8
hope that link actually works, if not search for the latest drives and then at the bottom of the page/driver details there is a link to previous drivers that brings up a page to manually choose an older driver.
hope this helps people actually play the game now.

edit: could a moderator change the title of this thread please to Fix for flickering overlay with amd gpu's, please instead of Fit for flickering amd gpu's, thankyou.