digg_url = 'WEBSITE_URL';
The fix is simply to change the single quotes to double quotes. WordPress doesn't send interpreted double quotes and your Digg widget renders properly in both locations. Since that was such a simple tweak, I've also included a div with a style that displays the widget on the right side of the text with the text wrapping around the bottom when the widget ends.
<div style="position: relative; float: right; width: 52px; margin: 0px 10px 0px">
digg_url = "WEBSITE_URL";