Has anyone else used a MiniDP to VGA adapter? I bought a cheap one and it works, but the image on the external monitor is not very clear - shaking a lot like the refresh rate is too slow or has scanning lines across it. Tried a few different refresh rates and it can be usable, but still not perfect. Tried it on a few different monitors and same thing so it's definitely not just my monitor. I've also tried it from the Thunderbolt port on my iMac and this too produces a poor image. So far I have a couple of theories: 1. Cheap adapter - bad performance. 2. Going from Digital signal to analog - inherently going to be poor pic. If 1 is true, I don't mind buying the one from Microsoft (even if the price is extortionate!) as long as it does the job properly. Just wondered if anyone else had used one and what there experience was?