Sets user interface level.
qn - No user interface.
qb - Basic user interface.
qr - Reduced user interface with a modal dialog box displayed at the end of the installation.
qf - Full user interface with a modal dialog box displayed at the end.
qn+ - No user interface except for a modal dialog box displayed at the end.
qb+ - Basic user interface with a modal dialog box displayed at the end.
qb- - Basic user interface with no modal dialog boxes.
Note
The modal box is not displayed if the user cancels the installation.
For example, to display the basic user interface options during the package installation, use the following command:
msiexec /qb Example.msi
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/sag_wininstall_command_line_syntax.mspx