Disclaimer - I work for Symantec (Norton) and my job is to work with our large customers to help them get the best out of our endpoint protection products and these views are my own (but based on fact).
Littlemissangrypants pointed this thread out to me; I just wanted to offer some advice.
No Antivirus product, paid or otherwise can guarantee you aren't going to get infected or have problems - anyone that says that simply doesn't understand the problem. It?s gotten far worse over the last couple of years too. Most traditional AntiVirus products work using "signatures" - these are generally looking for a specific bad file appearing on your computer. You can think of it as watching your DP/DH going out of the house in the morning dressed in black trousers and a white shirt and returning home in the evening in the same white shirt and black trousers. You recognise this person as your DP/DH and know its them - you have a "signature" for them. However, if they changed their appearance during the day and came home in an orange shirt, your "signature" which is looking for a white shirt wouldn't recognise them. This is the same way that most AntiVirus products work. Just a few years ago, we had something in the region of a million signatures we were looking for and AntiVirus worked really well then (and these million signatures had been built over 10-15 years). Somebody always got hit, then they submitted the virus to an AV vendor and they created a signature for it (sometimes we picked up the files before our customers with our collection systems) and with that signature, we could protect millions of customers. Sadly, the virus writers realised this and they have changed radically in the last couple of years. There is now a huge underground economy developed around writing virus software, much of it is paid for by organised crime.
Today, the viruses are changing so quickly, that we are adding 30,000 signatures every single day. Last year, we added nearly 5 million signatures (our total is currently around 20 million) and saw over 400 million unique viruses and it?s still increasing. Let me put that into context, that?s roughly 12 new pieces of malicious software appearing every single second of every single day for 2012.
This is what you are paying for when you buy AntiVirus software - you are paying for the huge amounts of research and development that go into building better protection mechanisms (the current trend is to look at behaviour and characteristics (i.e. you know much more about your DP/DH, how they behave, the length of their hair, eye colour, etc.) but all this technology costs money. (In Norton, that?s called SONAR and File Insight).
I'm not going to recommend anybody - I'm going to leave that to you to decide, but what I will say is that there are plenty of independent reviews of consumer AntiVirus products (including the free ones) - one great site is AV-Test - they have a large number of products under constant test. It?s also important to look at what Operating System you are running as different products can be more effective on one than another (of course a good product will get the same score on everything, but it?s not always possible due to the differences in the OS).
www.av-test.org/en/tests/home-user/
Quite often, the free products are subsets of the paid version. Companies with paid for products are not going to give their latest and greatest protection technologies away for free, so you may get last year?s protection technology for instance, rather than this years.
I'm going to close by returning to my original statement "No Antivirus product, paid or otherwise can guarantee you aren't going to get infected or have problems" as on your computer, you probably have a huge number of programs. I am willing to bet that you probably have Java installed, most likely Adobe Flash, Adobe Reader and other third party products? Every single one of these applications has had major security issues in the last few years (and continues to have them). If you are not patching those holes as well, then we are fighting a losing battle. Think of your PC like a castle, AntiVirus has closed the doors, locked the windows and drawn the curtains, but a third party product with a security issue has left the cellar trapdoor open.
So, choose your AntiVirus product based on what people say, read the reviews from the experts and choose something you are happy with but if Adobe pops up saying "please update me" or Java does the same, or even Windows asks for it then you should do it as soon as you can because you can bet that somebody is already out there being paid to try and exploit the hole in the program.
I'm not going to comment much on the Norton comments - except to say, check out what the reviewers say - many views are based on old product versions and the historical versions legacy - the new versions are fast, efficient and winning awards for performance and protection everywhere. Oh, and generally the price for Norton is for protecting 3 PC's, not 1.
If you have any questions, I'm more than happy to help.