The Holiday Screen Savers.
Here is another way to possibly infect your system. We have all seen them, they actually look pretty cool, but are they what you think they are?
Any free software you find on the Internet may not be all that "free". If you have to give an email address to download, more than likely you will receive unwanted spam in your inbox. You could also be installing malware right along with that cool screensavers of snowflakes falling on your screen or Frosty the Snowman dancing around.
Not all free things on the Internet are bad, but check what your are doing before you download and install the software, most will mention that it will also install some type of "spyware" in order to use it, and thats never a good idea. If something looks too good to be true, it probably is. No one wants to spend their Christmas money on removing spyware/malware/virus when that new game for your Xbox maybe right around the corner.
-Bryan