There is a Camera RAW Codec for Windows 8, which it sounds like you have installed already. It does not yet support the 6D. Microsoft, unlike Apple, is very slow to update RAW support for cameras. The last update was in October of 2012. Canon has their own RAW codec, but as far as I know it only works on 32-bit versions of Windows. I really wish Microsoft would be more on top of things. I'm dealing with the same thing right now with Nikon D600 RAW files that my friend gives me. I have to open them in Lightroom even though I didn't really necessarily want them in my catalog.