Richard Binning of Beside the Cursor blog has created and is sharing an application that will check the builds that are installed on a computer without requiring you to open Revit. It finds all the installation of Revit software on a given pc. It also works on a 64 bit operating system too. Here is an example screen shot.
Visit his BLOG POST to download the application!
Last, if you find his work makes your life just a little bit easier he provides an easy way to donate to his "charity" on the resulting report. Thanks Richard!