AVG, Avira, Avast, all are as good as the other. There are others too but those are possibly the most popular.

Be sure you Google your choice adding the word 'free' to get the right download. Then during the install also watch the choices so you remain on the free version

currently I am only suggesting Avast and Avira, AVG once a great product simply has had too many issues with version 8 to recommend it at this time, hopefully that will soon improve.

avast! Home Edition
on that page to the left are 2 pdf files to read the user pdf and the install pdf, they give all the info on how to install,register and set up AVAST. I am personally using AVAST now and like it.

Avira is also quite good however it will pop up nag screens wanting you to get the pay version. Other than that it is a good AV.
http://www.free-av.com/
How to disable nagscreen
here is the list from castlecops.
Lists of freeware antivirus

Personally I use AVG on one system and Avast on the other. I recommend either. Admittedly when AVG upgraded from v7.5 to v8.0 there were concerns though not everyone had them.

I have concluded from my readings that AVG might have not done enough testing on the v8.0 which is a combination of AV and a spyware engine. There were a couple of AVG .dat file updates that were buggy. Though inconvenient I can remember past .dat files for many big name products which have caused concerns. So I am not overly concerned.

Maybe it is because I have Avast on my secondary system so I don't have much experience with it, but it just seems a little harder to navigate.

At this time all and all I can't see you going wrong with either. Just be sure your choice is the free version.

DA

Not that it would matter with anyone nowadays, but with my old pc with a tiny 550 MHz cpu, Avast updates would significantly slow down the pc until it was finished updating. AVG never did.

I have Avg 8.0 on all three computers -- and never had any problems

I have used both AVG and Avast and much prefer Avast. I stopped using AVG almost two years ago. I just like the user interface of Avast much better, but that's a strictly personal thing.

I have AVG on my Vista home, and avast on my xp I like them both.

ravencajun, regarding your link to castlecops, apparntly it no longer exists and has shut down.- (see the msg on the webpage that pops up). Was/Is the list available elsewhere?

Try Googling 'best free anti virus', then look at a few sites offering comparisons. There is no real consensus on the 'best'. Quite simply if you are unhappy with the program you use then certainly try another.

What can we mere mortals use as a yardstick to decide good or bad? If you are able to surf the net without getting a virus the program must be working in my mind. I currently have the free version of Avast, Avira and AVG, one on each of my 3 computers. None seem any better or worse than the other so all must be equally good I suppose.

Sorry to see Castlecops bite the dust though, I always felt that was a good site.

My computer is about four years old and when I tried Avast, it slowed my computer down so badly that I couldn't even use it. It took me almost an hour to REMOVE Avast just so I could use my machine again!

Vacuumfreak, that may well be. But the possibility exists that Avast conflicted with another program already installed on your computer. Based on that can we blame Avast or the other program? At least you were smart, you removed it and installed a different program that played nicely for you.

It is extremely unfortunate that we have lost one of the best long time security help forums on the net, CastleCops. Much good information is now lost. I was a member there for many many years and am sad to see it gone. Other good forums with many of those members are now available which is good news.
Paul and Robin did an excellent job with CastleCops, I wish them well and will miss that place.

Another very good "list" site I often recommend is Gizmo's site. He has lists to many types of programs not just security so you will have to go to the appropriate area to find what you want.
Gizmo's List - The Best Freeware Reviewed and Rated

I had been using AVG Free for years.
Recently, an upgrade was required.
I decided to try some other Anti-virus programs, but they had to be 'free'.
It boiled down to Avast and AVG.
AVG won.
I had problems with Avast on several machines,
and no problems with AVG Free.

AVG Free is still the program I suggest if asked.

txKen

I have used AVG Free for years and still use it.
Pam

AVG Free for years on mine too--problem free.