MS just released 4 more security patches to prevent people from taking control of your computer - makes 6 in 6 weeks. also released one for Outlook Express.
Details: http://www.us-cert.gov/cas/techalerts/TA04-196A.html
Prior to the release of the last IE patch, US-Cert had advised people not to use IE due to security holes and MS sitting on fixes that wouldn't be released until XP SP2. Looks like MS took them seriously and is trying to pump out the patches for SP1. Might be a good idea to check for critical updates more frequently.