Hello,
I cannot install WiDi on my laptop either. I have a DELL XPS 17 L702x with an i7-2630QM and intel centrino advanced N-6230 as network adapter with the last driver installed (15.11.0.7) and also the needed software intel PROset/wireless (last version: 16.11.0). My OS is Windows 8.1, I updated it from Windows 8.
When I use the WiDi update tool I get the following message (see picture below "captura"). 
And when I try to directly install the WiDi software from the driver itself (last version: 4.3.4.0) I get the following error message (see picture "captura2") Sorry it's in Spanish but the message is quite clear.
I have searched the processor and I am sure it supports the Widi technology. I don't know what to do. I have reinstalled all the drivers several times, I have tried with an older version of Widi and I managed to installed it, however it gave me an incompatibility problem and I couldn't find any TV.
I would appreciate some help.
Thanks in advance
PS: Sorry if I placed the images wrongly. It's my first time
Edit: Regarding the answer to the other user, I think I am using the intel HD graphics since the icon appears as active instead of my Nvidia geforce 550M