You can always install the driver manually.
1-download
http://support.amd.com/us/gpudownload/windows/Pages/radeonaiw_vista64.aspx
2-Run installer so it extract all its content, for me it extracts all at:
C:\AMD\Support\13-1_vista_win7_win8_64_dd_ccc_whql
3-when the installation setup pops up close it.
4-Go to start, right click computer and choose properties.
5-then open the device manager (left column), click the + on display adapters.
You should see your Radeon HD 5670, right click it and choose properties.
6-Go to "driver" tab click update driver, and choose "browse my computer for driver software"
7-click "Explore.." and browse for the driver that should be at:
C:\AMD\Support\13-1_vista_win7_win8_64_dd_ccc_whql\Packages\Drivers\Display\W86A_INF
8-let it install and reboot.
9-To install CCC after reboot navigate to:
C:\AMD\Support\13-1_vista_win7_win8_64_dd_ccc_whql\Packages\Apps\CCC2\Core-Static-Net4
and run "ccc-core-static.msi"
DONE.
That should install the driver no matter what.