RunAs is a great way of temporarily elevating your privileges to admin level when you are logged on as an ordinary user. However, while you can right-click on .exe files and select Run As from the shortcut menu, this doesn't work with Windows Installer (.msi) packages.

Here's a workaround that makes this possible.

Credit for this trick goes to: http://www.windowsnetworking.com/kbase/WindowsTips/WindowsXP/RegistryTips/Security/InstallingMSIPackageswithElevatedPrivileges.html