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.
Manually open Outlook 2010 PST
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.