Using Multiple Personal Folders
Items you create and receive in Outlook 2007 are stored in personal folder (.pst) files. The default location for .pst files is \Users\<user>\AppData\Local\Microsoft\Outlook.
If you don’t use Outlook 2007 with Exchange Server, you use personal folders for storing your Outlook 2007 information and data. (With Exchange Server, your messages, calendar, and other items are stored centrally on the server, although you can use .pst files in conjunction with an Exchange Server account.)
You can create multiple personal folders to help you organize your data. For example, you can store e-mail messages associated with a project or a client in one folder and store other messages and items in a more general folder. Another useful ...