Want to Upgrade Outlook or Convert Outlook 2003 to 2007? In Microsoft Outlook older versions (97, 2000, 2002/XP), which you might be using, ANSI PST files have the maximum size limit as 2 GB, beyond which, your application corrupts. You can protect your PST file against this corruption by upgrading Outlook PST from ANSI (2GB) to Unicode PST (20GB). PST size limit increases and prevents corruption. But some times users want to convert their Outlook 2003 PST files in Outlook 2007, It means they upgrade their outlook environment to Unicode (2003) to Unicode (2007). Outlook 2007 has some latest features like large storage limit, as new calendar sharing, Instant search and the To-Do Bar, you can organize and instantly locate the information that you need. Software provides you easy user interface and easily upgrade and degrade of Microsoft Outlook. By using this utility you can successfully convert Non-Unicode (2 GB) to Unicode (20 GB). The process to convert old PST to new PST (i.e. from ANSI to Unicode, which has 20 GB maximum file size limit) can be performed using a PST converter upgrade Outlook data file and thereby, extend PST data size. SysTools PST Upgrade and Downgrade successfully runs with Windows XP/2000/2003/Vista and Windows7 Operating System Using this tool user can quickly upgrade or downgrade PST files in few mouse clicks and key strokes. Easy to use with highly interactive user interface, User is not required to have any technical knowledge while using this tool.