Here's a good argument not to use IE: any site you visit can access your system clipboard.
Firefox is here for a reason!
This page is a live demonstration of this vulnerability. Make sure that your clipboard is not empty (has got some text in it) and refresh this page.
If you're running on IE bellow you will see the contents of your clipboard.
If you have seen the contents of your clipboard above this means that any malicious site you have visited before may also have gained access to it via javascript and may have secretly posted it back to its owner.
Information gained via http://www.1060.org/blogxter/entry?publicid=182730D4B28DE09F55361F6DD53A1AC5 which in turn points back to http://isc.sans.org/diary.php?date=2005-08-30 as the original source of information.