David,
for casual viewing in Windows I use XnView (http://www.xnview.com/) and if I want to be really sure, the best is Exiftool by Phil Harvey (http://www.sno.phy.queensu.ca/~phil/exiftool/). As a test picture I actually used one of the sample pictures attached to the IPTC specs, so the metadata I started with should be really correct.
Regards,
Zdenek