How viruses damage our PC and how do they affect it:
We have all asked ourselves if we are really immune before the attack of a virus or if our antivirus software can really protect us a hundred percent from a virus, the answer is no, nowadays this is impossible, due to the fact that every day there are new and more complex viruses been developed, also because more security failures in the operative systems are shown, the only chance we have got is to reduce the risk as much as we can.
Check this page for more info:
http://www.seekinusa.com/computers/how-viruses-damage-our-pc.asp
Regards !