Hello,

There are couple of good antivirus softwares available on the internet for free. You can try using AVG or Avira.

Here you go...

http://www.avast.com/eng/download-avast-home.html

Hope this helps!

You can get bitdefender in torrent site its really good and it does not use much of your system resources...

Don't got with the bit defender. I've been runing the same programs for 4 years and have not had any problems with my pc.
Just look them up on google. sorry i'm at work and it won't let me to the sites for links.

SuperAntiSpy
Avast Anti virus
i'll also recomend zone alarm and malwarebytes if you really want to be covered