"Exifer is a nearly free software (you only should send me a postcard if you're using Exifer frequently) with which you can manage the metadata (EXIF/IPTC) of pictures taken by digital cameras. Because many image processing software destroys this metadata when saving such files, the idea was to create a backup of the metadata before editing it in any software, and then, after that to restore it back into the processed file. With Exifer you can do this very easily."
If you're looking to be an EXIF ninja, here's a throwing star for your belt. ;-) I really like ACDSEE for things like this myself, because I can mass-change the timestamp on a file based on the EXIF photo date field.