I used forced install from standard drivers, and they worked fine.
For compatibility reasons, I used Catalyst 10.2 driver (with v9.1 and v12.1 as "backup").
"Forced install" :
You let installer unpack to AMD folder. After it's done, exit driver installer and go to Device Manager.
GPU's => Your unknown/VGA standard card's propreties => Update driver => Manual installation => Browse to AMD folder installer created and find Video driver folder.
Select file with driver info from it, and then pick "HD2600 XT" from list of GPU's.
Confirm installation of manually selected driver and after it's done, restart Windows.
You may need to do manual installation twice (since sometimes there is "Secondary" GPU found by device manager).
At the end, it should look like this (GPU-z window) :
The attachment 3DMark 03 HD 2600 XT 512MB mini.PNG is no longer available
Good luck 😀
PS. Bit of warning : If you pick wrong driver (or the one you pick won't be compatible with your exact card), you will have to enter Safe Mode and delete faulty driver manually.
Protip : Check how to enter Safe Mode, BEFORE you start tinkering with force driver installation.