What is the WORST a virus could do to your computer?

[Grrr..]

The worst and increasingly common is to steal passwords and monitor keystrokes then send them to a baddie.Identity theft is very popular nowadays and baddies want to harvest as many personal details as they can.

The next level is to use your computer to send spam and to launch 'DOS attacks' on some website the baddie wants to bring down.DOS (denial of service) attacks require a lot of computers to be infected and to be under the control of the baddie.'Botnets',they`re called and they can be bought and sold by criminal types..

Then there are the advertising related viruse/spyware that just push ads in your face and direct you to web sites.

And of course the fake programs (fake anti virus programs..fake tune up programs etc) that tell you that you have a virus or a computer problem and that you have to buy the program to fix it.

As for the best anti-virus : Educate yourself about viruses and spyware (see above).
That is the BEST security you can have.

If you want a program or two to help you : Comodo firewall (free) and Avira anti virus (if you must have an AV)
If you want to pay for a program (some people feel safer paying) then 'Nod32' is good and Norton 360 is half decent.