I have recently downloaded the standard package which suggests that it is supporting DX 10, however the option is disabled for me... In case I had a problem with the driver I downloaded and installed the latest catalyst one
10-10.

My pc specs are:
CPU: AMD Phenom 9850,
Mobo: Asus M3A78-T,
GPU: Sapphire 4850 512MB
Ram: 4GB DDR2 dual channel Kingston
PSU: Chieftec 550W
OS: W7 Professional x64

Why is DX10 disabled for me?