well - they may be your saved e-mails, too - you may not want to delete them
or - they could be address books and other data
are those files in the Documents and Settings folder or a sub-folder ?
they are GUID's - you may be able to search the system registry to learn what program they are for
something i do quite often is to rename or move folders and/or files to another location, rather than deleting them
that way, if bad things happen, you can put them back

if everything seems fine (after a considerable period of time), then i may delete them
maybe you could make a more permanent backup of them on a CD or something (CD's are cheap)
i am guessing these are actually folders - not files
inside the folder may be some files
either way...
you might look at them with HxD to see if they are something recognizable