I have a similar problem.
My current spec.: Lenovo G500, Ati Radeon HD 8750 M with old AMD Video Driver for Windows 7 (64-bit) version 126.96.36.199 (from Lenovo official website).
I need to install the latest AMD Catalyst 13.12 WHQL driver from http://www.guru3d.com/files_details/amd_catalyst_13_12_whql_download.html
but when installing it my GPU is not detected and not recognized
After finishing installation video driver isn´t in device manager (Win 7 64b).
Could you tell me how you have resolved your problem?
Thank you for your answer.
Have a nice time.