It depends on whether you installed the Windows XP Upgrade, AND chose the
Quick Upgrade, which would keep your existing data files. If you opted for
a New Install, all your data files are gone. If you did do a Quick Upgrade,
search your drive for *.dbx files (dbx is the file extension for Outlook
Express mail folders, e.g. Inbox.dbx). If you find the files (you'll know
by date and size if they're the right ones), take note of the path to the
folder where they are. Then open Outlook Express, click the File menu,
click Import/Messages. The wizard will open, select as the program to
import from: Microsoft Outlook Express 6, click the Next button. When the
next window opens select the option to Import from an OE 6 Store directory,
click the Next button, when the next window opens click the Browse button,
and then navigate to the path of the folder that has your old .dbx files.
The rest of the wizard is self-explanatory. The above assumes that Outlook
Express was your old email client.