My MBox does work as an audio interface in Reaper with Win 7 64bit. Trick is you first have to get the MBox installed which requires you to install PT LE. Which is apparently the problem you are having.
My short term fix was to Download Reaper (both 32bit and 64 bit versions). Then buy an Audio Device which has a Win 7 driver (for example an Audiophile 192). Then, like many others, while you wait for Digi to support Win 7 with the MBox, learn to use another recording application.
