I thought it would be wise for me to warn my readers about a disturbing virus that has been making its rounds since November. Conficker.
This virus is a great example of how well-engineered viruses operate. The Conficker virus can replicate through many different channels; USB sticks, Networks, the Internet, and a few other places. It embeds itself so deeply in your system that it is difficult to root out.
It is expected that the virus will be making another large attack today. Good anti-virus practices should do the trick to keep it at bay, but be cautious about which networks you go on (coffee shops, etc.), due to the fact that it replicates over networks. Remember, the best way to prevent getting a virus is to leave your computer off and never turn it on.
Microsoft has an excellent writeup on this dangerous virus, with removal instructions.