Here is an update about the DownAdUp/Conficker worm. The latest estimates are that DownAdUp/Conficker has infected over 9 million computers. As of now, DownAdUp/Conficker mostly focuses on spreading to other computers. DownAdUp/Conficker doesn't do anything really destructive like deleting your hard drive. However, it is still best to get this virus off your machine if you have it.
To get rid of DownAdUp/Conficker, update your virus scanner and run a full virus scan. It should be as simple as that.
To keep your computer from getting infected, make sure to have a Spyware Scanner and Anti-Virus Scanner.
For a full guide on keeping your computer safe and running smoothly, or if you don't have a virus scanner, check out my guide that I wrote here. It includes a link to a virus scanner that I recommend.
Edit: Updated number of infections. (01-21-09)