The method by which your emails are stored depends on the type of email account you are using. If you are using a POP account, your emails are stored in a .PST file that should be located in the Outlook Files folder under your My Documents folder (if you're using Windows 7). This file is generally not deleted when uninstalling Office. It is always a good idea to make a backup of the .PST files before installing or uninstalling, just in case.

If you are using an IMAP or Exchange account, then your email is actually stored up on the remote server, and also will not be removed when you uninstall.

Hope this helps.

-SW