To the left you see the Windows Vista thumbnail for a Canon RAW image before I installed the Canon 1.2 CODEC for RAW images. To the right is the same image thumbnail after installing the CODEC. There is such an, um, nothing much, huh? I also downloaded the free Microsoft Pro Photo Tools from the...

Microsoft Pro Photo downloads area

However, that didn't show any thumbnails either. The Canon provided RAW CODEC for Vista does work with Windows Photo Gallery, however. So, the entire exercise was not a complete waste of time.