this virus has been around for a little while now, what's new is the fact that researchers have discovered that it will be receiving new instructions on April 1st. If you're running windows XP, make sure you have service pack 3 installed, and your antivirus subscription current and up to date. If you're running any windows 2003 servers then make sure you have service pack 2 installed. If you're running windows Vista, make sure you have service pack 1 and all subsquent updates installed via windows update (all critical and recommended updates).
if you're running any windows previous to XP then make sure that you have ALL of the updates installed, and your antivirus is up to date and scanning real time. The usual precautions still hold true, do not open any unsolicited attachments, if in doubt verify that the person actually sent you something. if you're opening attachments, best practice is to SAVE it down to your C drive first (i.e. to My Documents) and then open it, that way the antivirus software has a chance to scan it before it's actually launched. It will not stop everything but it has a better chance of catching something, as just running it from the attachment only allows the virus scanner milliseconds try and figure out if it's good or bad, and by the time it stops something bad, the damage is already done.
Also remember, NO company will ever send you a file to "patch" your system via email. Most will send you a link, and usually after a discussion with tech support. Never will they send you anything unsolicited so don't open any "updates" recvieved via email.