My current pc is windows 7, I am not able to access my stored sent messages from my old windows vista pc ( only a small percentage are showing in Wnidows live mail)
First we would need a little more information.
What was your old email client on the old machine? Outlook? Outlook express?
Second did you copy over the pst file to import into the new machine?
I would suggest you to read this article which should help you do what you need.