PatI use a freeware utility RenJpg.exe that enables you to rename files in any format you wish it and can keep them in order of date/time taken. I used it to sort out the Christmas Market trip photos from various people - would have worked if everybody had their camera clocks set properly!
See http://www.freeware4pc.com/utilities/renamejpegfiles.shtml for details Derek==========================< U3A Aylesbury Vale> ========================