Microsoft has released a critical patch for IE, outside of their typical once a month "Patch Tuesday" cycle. The reason is that this is a doozy, and it's being exploited. Internet Explorer users, here are my recommendations, in order of highest security to lowest security:
1. Replace IE with Firefox. The minor reason is that Firefox simply doesn't do ActiveX, which is a sewer of security badness. The major reason is that the Mozilla team is much, much faster to get security updates out. Days, not weeks. You find Firefox here. Or you could get Google Chrome (although Google is Evil) or Opera. Both are a security upgrade over IE. There's just less malware focused on Firefox, and way less malware focused on Chrome or Opera. That can always change, but that's the current state of the 'Net.
2. If you are still on IE 7.x (or Lord help you, IE 6) upgrade to the latest version tout suite. IE 8 is OK, and IE 9 is even better. You get Internet Explorer downloads here.
3. Apply the danged patch to your current Internet Explorer. This will make me sad if you do it, but hey - your browser, your security.
Me, I got an overdoes of Internet Explorer hate back in the 3.x days, switched and never looked back. The others work great, taste great, and last a long time for your chewing satisfaction.