I've got the latest Canon raw codec version 1.7 which you can't view CR2's in windows 7 64bit.
I then downloaded Windows live photo gallery and added my main .CR2 folder to windows live photo gallereries index(top left hand corner).
After Windows live indexed all the .CR2's they can now bee seen in Windows when browsing my pictures folder etc.
Have you tried xn viewer? Works well for me, and it does read canon .CR2
Edit; im on 64bit windows 7. Works perfectly and you can import them direct to photoshop to.
Windows & Mac compatible
I've got the latest Canon raw codec version 1.7 which you can't view CR2's in windows 7 64bit