Why? The changes Intel has made to WiDi since its original release have been significant and as such anything but the latest drivers results in a substandard experience with the Belkin ScreenCast.
At the time of writing the current version of WiDi is 188.8.131.52, which adds support for WiDi built directly into TVs while the previous edition brought H.264 hardware encoding for smoother playback and lower latency. One release before that introduced support for 1080p video, HDCP 2.0 copy protection and Surround Sound. The version of WiDi software we found pre-installed on our Ultrabook lacked any of this functionality. Needless to say you'll need the latest Intel HD graphics driver as well (version 15.22.xx or later) to make this all come together.
Once this was done we still found the wireless image sent to our TV to be gaudy with oversaturated colours, needing calibration. WiDi is easy to setup, but to get it performing optimally takes a little more elbow grease.
The good news is jump through these hoops and WiDi lives up to its promise. Given it relies on Wi-Fi, it has the same distance limitations. But since you will use your laptop as the remote control it will be in the same room as your ScreenCast, making this a non-issue.
Intel's insistence on a Sandy Bridge chip for WiDi is partly because it has copy protection built-in at a chip level, but equally important is it ensures a minimum level of performance and this will see both 720p and 1080p content run smoothly. Audio also does what's said on the tin, outputting in 5.1 Surround Sound should the source content have it and connection to the ScreenCast automatically switches the audio output from the laptop to the TV.
Ultimately then what we have is a product that (after a few software updates) does exactly as it claims and once setup achieves it with the very minimum of fuss. So why can't we give it an unreserved recommendation?
In short: price. As it stands the ScreenCast retails for a hefty £89.99 and for £30 to £40 more you could buy a cheap nettop PC. For those determined to use their laptops equally they could simply keep a spare HDMI cable, connect to the TV for an entirely setup free wired connection and buy a wireless mouse for under £15. This method would also keep the fan noise of a whirring PC away from you during viewing.
The Belkin ScreenCast is a difficult product to rate. Drivers should really update automatically, but ultimately it is easy to use, streams HD video reliably and is a simple way to wirelessly extend your desktop to any TV… provided you have any Sandy Bridge laptop. That said the role of the ScreenCast is essentially little more than a dongle and what convenience it adds is compromised by a near three figure asking price. If you are prepared to accept the costs you won't be disappointed, but should WiDi continue to gather momentum we can see such devices quickly becoming commodity items and eventually - as Intel strikes TV deals - potentially unnecessary.