Many people underestimate the importance of updating their anti-virus definitions and usually end up getting infected by some random trojan or worm when it could ave been perfectly preventable by a simple update of 
definitions.
Anti-virus programs are very simple to update – some even do the updating for you. But if that’s not the case, you can always update at least twice a week manually, of you feel that updating everyday is too much of a hassle. You should also do a full scan of your computer at least twice a month to make sure that everything’s free from any lurking viruses. Also remember to do a full scan of any portable hard disks or flash drives that you’re plugging into your desktop computer or laptop.
