Microsoft has released a patch to fix a critical flaw in Internet Explorer.

This flaw is being actively exploited to compromise machines and install malware/spyware/rogue programs, so please run Windows Update and download the update immediately. Even if you don’t use IE for the majority of your browsing, other programs may use its underlying engine to display content.

Mozilla just released updates for Firefox 2.0 and 3.0 as well, to fix its own set of security issues. Be sure to run “Help” > “Check for Updates” in Firefox to update to the latest version.

Also please note: Firefox is the last security update that will be released for Firefox 2.x. If your system supports it, you should upgrade to Firefox 3 as soon as possible.

Keeping your browser of choice up-to-date is imperative. It’s your first line of defense against the bad side of the web.