SysTools PSTUPGRADE is an easy-to-use tool that has two main useful uses. The first use is to downgrade your Private folder file (.PST) exported by Microsoft Outlook 2007 so they can be imported by Microsoft Outlook 2003. The second use is to convert the (American National Standards Institute) Ansi .PST file format exported by Microsoft Outlook 2003, which supports the size limit of only 2 GigaBytes, to Unicode .PST file format which can support up to 20 GigaBytes - as this increases size limit and prevents data corruption after exceeding the size limit of 2 GigaBytes. This will make opening of your private folders created by Microsoft Outlook 2007 on Microsoft Outlook 2003 and upgrading the size limit of your folders possible. The demonstration version of this program supports only converting the first three folders of your .PST file. You can find more step-by-step instructions explained with screenshots on the program's informative documentation which can be easily found by clicking the "Help" icon on the program's window.