It looks like a lot of you are pretty savvy about catching virii but just in case here is this:
Got a note from our IT dept warning us if we receive a warning message that your computer has been infected by the sasser virus DO NOT click OK. Instead, click cancel to avoid infection.
Patch all of those NT/2K/XP boxen and you'll survive this one. The MS Baseline Security Advisor is a handy tool also (microsoft.com/security). I use to scan the subnets I manage to see who needs to be patched (esp since some of the nets I share with others).