Here is the TOP 3 antivirus and internet security suite in the market, as per 2009:
I personally use 'AVG 8.5.X' for my laptop. I am using various version of AVG from last 2 years. It has always been up to my expectation in providing security to my system from various viruses. Along with that I am also using 'Spyware Doctor 5.X' as anti spyware for my system. It is always suggested to have specialized software for antivirus and spyware. Both the above software are of free version and still they do their task properly. Best part is the software get updated everyday with latest threat database, for free, once you are connected to internet.
If you want to buy a software for your system protection from virus, then I will suggest you to go for 'Kaspersky'. I have purchased it for my desktop and it works good. It cost me around Rs 800/- for a single system license.
Hope this helps you in selecting an appropriate protection for your system.
Hey buddy i think the avast premium edition is the best of all.. It provides you over all protection for your system... The best thing is that you can download the update file from http://www.avast.com and save it on hard disk... And it provides 7 types of protections.. So choose wisely..