Ok well some of the guys on IRC spent a few days compiling a GPU miner binary for Windows and it looks like they finally got it to work. Can't guarantee it will be bug free or work as well on Windows, but give it a try and see how it goes.

Download Link:
https://www.dropbox.com/sh/56lnq52g4gny0m0/AADMJa2QTMSSc4g9gx1BfWIla