If you upgrade from Outlook 2007 to Outlook 2010, your .pst files will auto-magically be imported into your Outlook profile. You don’t need to do anything (beyond upgrading) to get them there.
If you want to do a clean install where you uninstall Outlook and then install Outlook 2010, you may need to manually import your .pst files into your profile. As with Outlook 2007, it’s easy to do in Outlook 2010 but the commands to do it are in a different spot.
Here is one way to do it in Outlook 2010 Beta:
1. In Outlook 2010, click the File tab.
2. Click Open and then click Open Outlook Data File.
3. Navigate to the .pst file to import and then click Ok.
If you or your organization isn’t a fan of .pst files, check out the Personal Archive feature with Exchange Server 2010 and Outlook 2010. As with .pst files, the Personal Archive feature does not affect user’s primary mailbox size. The difference is that the e-mail archive folders are stored on the Exchange server and can only be accessed while the user is connected to the internet. Users can access their Personal Archive just like a .pst file in Outlook 2010. Because archived email is stored on the Exchange server users can access it from OWA as well. For more information about the Personal Archive in Exchange 2010, see Understanding Personal Archive (http://go.microsoft.com/fwlink/?LinkId=178303).
You can also disable .pst files in your organization. In Planning for Messaging Records Management 2010 Help (http://go.microsoft.com/fwlink/?LinkId=178295), see the sections “Limiting Access to PST Files” and “Configure user's systems to prevent moving or copying Exchange mailbox data to PST files”.
And while I’m on the Exchange Server 2010 tangent, you should definitely check out the new features available if you haven’t already. See Microsoft Exchange 2010 (http://go.microsoft.com/fwlink/?LinkId=163579) and What's New in Exchange Server 2010 (http://go.microsoft.com/fwlink/?linkId=164425).
Happy Office 2010 Beta evaluating!