What is a good antivirus program out there to use?

I purchased a used computer about 10 months ago and the guy had put Norton Antivirus on it before I bought it. It is now up for renewal and I don't know if I should renew it or not. Is having an antivirus necessary? What are some good programs? Are there any out there that are free to use? Should I stay with the Norton Antivirus? Please help me....I only have 6 more days left with this antivirus left.

What is a good antivirus program out there to use?free anti virus

Having an up to date anti-virus is very important (it only takes 2 minutes on average for your computer to be compromised). Norton is bloatware and I would not recommend it at all. If you want to pay for an anti-virus Kaspersky is the best. If you want a free anti-virus I recommend in order of popularity, but I leave the decision to you (install only one):

1. AVG Free

a. A simple interface

b. Can detect about 82.82% of viruses

Cons: low virus detection

2. Avast!

a. Real-time protection

b. It has an option to delete a virus once found

c. Can detect about 87.46% of viruses.

Cons: Too many icons and confusing user interface

3. Avira AntiVir

a. It can detect malware better than Avast and AVG

b. It's cute umbrella icon

c. Can detect about 94.26% of viruses

Cons: A very sluggish update