When viewing a folder with the "Thumbnail" view, Windows XP creates a "thumbs.db" file in that folder. This is a cache of the current pictures in that directory. If you want to remove this feature to save disk space, start by going to "Windows Explorer". Go to Tools > Folder Options > View. In the first section under "Files and Folders", check "Do not cache thumbnails". Now you can search for the "thumbs.db" file on your computer and remove them. Once you do this, no more additional Thumbs.db files will be created.