I feel there are 3 aspects to protection, no one product does more than one well:

Firewall - the standard is ZoneAlarm. You can get a free edition from CNET Download.com. Very interesting to see what on your machine trying to connect out to the internet.

Antivirus - you will hear people argue about Norton, McAffee, etc. Each gets different ratings each year. I personally use AVG Free because I am cheap.

AntiMalware - the standard is Malware Bytes. You get find a free version at the usual places. I suggest people spring for the paid one, so that it stays in memory all the time and PREVENTS problems rather than cleans up afterwards. You can get an e-mailed key to upgrade the free one to the pro from Newegg for around $20. I have literally never heard of anyone ever say anything bad about Malware Bytes, and have seen a LOT of people thanking the company for cleaning up their machines.

That is all.