PST files are the database files of Microsoft Outlook and ANSI and Unicode are the application formats of it. Earlier Versions of Outlook (2000, 2002 and 97) has ANSI application format while, Newer Versions of Outlook like 2003, 2007 and 2010 (32-bit) has Unicode application format. ANSI has a size limit of 2GB and Unicode has size of 20 GB. Outlook XP is the 2002 version and it has ANSI application format.
So, if you are an Outlook XP user and you want to switch to Outlook 2007 due to some purpose then, PST Upgrade software is one improved solution for upgrading from Outlook XP to Outlook 2007 and remove PST 2GB Limit.
PST Upgrade is one impeccable utility program to execute converting of Outlook XP to Outlook 2007 file because it maintains all those things, which are necessary in better upgrading and degrading processes.