Hi Mate,
If you go to this website "Link:
URL http://www.av-comparatives.org" you will see they have tested
a variety of antivirus software; both free-edition and pay-versions.
If you have a visa of something similar this website recommends "F-secure" which is an antivirus you have to
pay for; but you can get a trial version of this to see how it performs on your laptop.
If you want to free edition of antivirus get "Avira antivirus".
Here are the summary result of avcomparatives virus testing "Link:
URL http://www.av-comparatives.org/images/stories/test/summary/summary2010.pdf"
P.S. I personally like to use 'Norton 360 or Norton Antirus'.
All the best,
-Brent907