Tomorrow, the next Microsoft Patch Tuesday round takes place whereby those with Automatic Updates enabled will be fed the latest security patches.
There is however a nightmare scenario which, instead of updating machines, could compromise security by downloading malware to systems which haven't installed the emergency patch called KB2718704 issued by Microsoft on 4 June.
For a brief explanation of how things could go pear-shaped if you don't install the patch, see this article: https://isc.sans.edu/diary/Microsoft...Security/13429
A more in depth article which makes fascinating reading can be found here: http://rmhrisk.wpengine.com/?p=52
You check whether the KB2718704 has been installed or not by by going to "Add/Remove Programs" in Control Panel and then in the list of installed programs, check the installed security updates list. In Windows XP, it looks like this:
In Windows 7, go to "Programs and Features" in Control panel which should provide a similar view.
If you can't see it in the list, you can download it from here: http://support.microsoft.com/?kbid=2718704