While it works fine in good browsers, IE bugs out because the markup is technically bad. Line 270 of the main file for the plugin has extra periods and single quotes around $target, causing the markup to look like this:
<a class='rsswidget' href='whatever.com/feed-URL' title='Syndicate this content' . target="_blank" . '>
Easy fix but wanted to bring it to your attention. Thanks for the plugin!