Go into Outlook Express, click tools/options and select the maintenance tab. There is a button called store folder, click it, and that will tell you where Outlook stores your email. I have both the Win2k and Win98 versions of Outlook setup to look in the same directory/same drive - eg. c:\program files\email\, and then if you are in either win2k or win98 you will get the same email in your inbox.
Hope it helps.