Vista - RAW and Photo Gallery

I've been organizing my collection of photos using tags from Windows Photo
Gallery. I do a lot of photo work with Canon digital SLR's and often shoot
in RAW format. I've just read that there have been problems with image
files with metadata attached (from some cameras etc.) when tags are used
from Windows Photo Gallery. I read that Windows Photo Gallery would often
times refuse to open the image but more frightening, that it actually
corrupted the photo file. The guy reporting this seemed to believe it was
unique to the Nikon digital SLR's. Can anyone she further light on this for
me? Am I risking corruption of image files by tagging them in Windows Photo
Gallery? If so, which files do I need to be concerned about i.e. RAW
images, CR2 Canon etc.

Barry