When I used to run WDP, I had no problems installing AMD GPU drivers and it's utilities to my knowledge. I forget what version of the drivers I was using though...
Does the drivers install properly? You are running 64 bit version of WDP, am I correct because this drivers set was for all 64 bit version only. Which card do you have?
I was running 64-bit version of WDP, the drivers did not install at all, it just got stuck at that one part which caused nothing to install at all. I have ATI HD Mobility Radeon 4250/5470, should be switchable graphics. It worked in 7989, it doesn't work at all in WDP.