Just had a client inquire about these files, and thought some of you might want to know as well. They are a Windows thumbnail cache files, and can safely be deleted. You can also turn off the feature; two sites will tell you how. The first works for Windows XP machines, and was written by Leo Notenboom. It can be found here. For those of you with Windows 7 machines, Fred Janssen has your steps here.
Excellent Nancy. I literally ran into these today for the first time and could figure out what to do with them. Thanks for answering my unasked question. -Cindy