I upgraded to windows 8 a few weeks ago and have since gone back to windows 7.
I have also recently upgraded my graphics card to take advantage of the capabilities in Photoshop. It turns out that there are / was a few driver issues with AMD/ATI and Photoshop and to a lesser degree Lightroom. Unless you are using a nvidia or intel based card or this issue has been sorted over the past few weeks then I would stop with windows 7 until they can release a driver that solves the issues. The issue is well documented and the only real way of preventing it in photoshop at least is to reduce GPU usage. I did also have an issue with Dfine crashing as well.
On a side note, Classicshell is fab and was one of the fist things I installed when I did my windows 8 install.