I am not familiar with 7 but I have lived the dream of the ATI installs.
The ATI drivers require .net software , yours specifically will be the 64 bit version .net 2.0
Upgrading from Windows XP to Windows 7 - Help & How-to - Microsoft Windows
Sequence
Remove all ATI software from machine. This should leave a generic driver for basic gpu functions.
A lot of folks have had issues caused by leftover bits of ATI drivers
Install and then update the .net programs
The install package from Micosoft will need updating for security related issues
With machine connected to WWW , Install your specific ATI driver(s)
When the drivers are first installed they connect to the www, I dont know why(sorry)
I Hope this helps out.