For how to convert PST emails to PST 2007 format, apply the Outlook PST Upgrade tool and increase PST file size from 2GB to 20GB. The PST Upgrade tool allows users to convert PST contact list to PST (means ANSI to Unicode or Unicode to ANSI PST file format) and upgrade Outlook personal folder at ease. By using PST conversion utility you will be able to upgrade your PST folders with all email metadata information (to, from, cc, BCC, sent and received date/time, attachments etc.) but the Outlook upgrade software can not convert corrupt PST file (already exceed 2 GB). Demo version is available at cost free that allows you to convert only first 15 emails per Outlook folder of the current PST file and you will be able to test their conversion capabilities. But if you want to upgrade your all ANSI PST then get full featured software at reasonable cost just at $49 (cost is applicable for only single user). Read more: http://www.pstupgrade.com/increase-pst-size-limit-20gb.html