Including selectivizr.js is causing IE8 to not display/render anything at all, but IE8 in IETester manages.
It also downloads everything, I can see that in the activity
It sure looks to me as if you've got code on the page referencing "jQuery" before the jQuery library is actually loaded. Your sample page gets an "Object expected" error from the first line of code that references the library (right in your "about" page).
The code appears to be setting up a "click" handler for a submit button.
Other than that, however, the preview page renders in IE8 and there's no "white screen of death."
edit — works fine (other than the "Object expected" error, and the related "submit" button of course) in IE7 too.