temporary files

We have all seen users open an email attached file - do some work on it -
then close it - user thinks their changes will be save to the attachment - do
we all know they are not.
so the question is...where is this file?
user opened attachment (excel file) from gmail - done some work - even said
they saved it - closed the file - wanted to return the file - but now cannot
find it.
user has windows vista home and office 2007.
in windows xp you could find the file in temporary internet files.
i have searched the entire system - hidden and system files included but
with no luck in finding the file.

help!

thank you all, Dave