Those burdened with using Microsoft Windows as their primary operating system should immediately update their installations in order to fix a recently unveiled flaw wherein Windows metafiles can be used by nefarious nogoodniks to install and execute malicious code/software such as adware and key-loggers.
The flaw is such that simply viewing a web page or email with images in it can cause your system to be exploited without any further action necessary on your part. As you can imagine, the security implications associated with this are enormous.
As an aside, it’s worth noting that the increasingly popular alternative web browser Firefox is not vulnerable to this exploit, so if you are still using Internet Explorer I highly recommend that you make the switch and avoid using IE when at all possible. Firefox is free. If you use Outlook for email, switching to Thunderbird - which is also free - can also help protect you. I do recommend turning off HTML email display, though, no matter what email client you use as there are security and privacy issues inherent to inline display of remote images in email.
If you’re at risk - and pretty much anyone using Windows is at risk of something at some point - I highly suggest that you download a fix recently released by Microsoft and apply it to your system.
While you’re doing so, it probably wouldn’t hurt to take a moment to consider a more long term solution to protect yourself from these types of exploits.
Firefox isn’t affected? Thank god. I’d heard differntly (over at Something Awful). I patched my system anyway, though I don’t touch IE except for window’s updates.