Although Hawkeye22 provided the best/easiest options. There are a couple of others.
(1) you can port (Not an install) Windows vista winmail over to a win 7 system. Did that on my wife's new win 7computer. She liked Vista Winmail and did not want to switch. Not a simple procedure as (a) you need to change admin privilege on vista to user and copy the folder to a USB stick, then change the adimin privilage to give user full control on the win 7 system, rename the folder to Old whatever and then copy the vista winmail folder over and finally run the dot exe.
(2) For die hard Outlook" You can use a copy of uSoft Office with Outlook included and install that. Note this would not be outlook express, but the full version of Outlook. This is what I did for my Win 7 computer, and then I exported My emails from my vista computer (winmail) to Outlook on my Win 7 computer.