It appears that the KAK worm is going around our merry little group here, I got it from a Mudcatter last night, but I had the security settings on Outlook Express set high, and so the worm was intercepted. The link Jeri provided above is very informative - here it is again (click).
I suppose it might be an idea to give a list of suggestions:
Always use antivirus software, and download updates to your antivirus program at least once a month.
If you use Windows, visit http://windowsupdate.microsoft.com/ at least once a month and download any critical "product updates" that are suggested.
Be Particularly Cautious With E-Mail
Don't Trust E-Mail Attachments. Files that end with the *.exe extension are the ones most likely to cause problems, so I'd suggest that you never send and never open *.exe programs that come by e-mail. When I got home from vacation last week, there were 384 e-mail messages waiting for me, and my e-mail got a bit cranky about downloading it all. Several people sent me the same JPG (picture) of a ballot - it was cute (and safe) - but maybe it would have been better if they had sent me a link to a site on the Web where I could see it. Somebody sent me a ballot thing that had an EXE extension, and I deleted that message and attachment without taking a look. Be very careful about e-mail attachments, and open them only if you are quite sure they are safe - the worst viruses can come to you from your best friends, who have no idea they're sending something bad to you. If you do have good reason to send an attachment, make sure your accompanying message and message title say something specific, something that could only come from you.
Keep your e-mail security settings high. E-mail worms like KAK can come as part of the body of an e-mail message, not necessarily as an attachment. If you even view an infected message as an HTML document (instead of text) you can be infected. If you use Outlook Express, go to Tools and select Options, and then go to the "security" tab and be sure Outlook is set to the Restricted Sites zone.
If you alert others about viruses, be sure you're sending valid information, not a hoax. Check out the information at a reputable antivirus site like McAfee or Symantec before forwarding virus alerts.
Don't get paranoid about viruses, but do use common sense.
Hope that helps. -Joe Offer- (some information stolen from Jeri's messages)