The best free security software

[Baserk]

"What is the best free AntiVirus / Firewall / AntiMalware program?"
Many times I have read the same question here on NBR, so about 5 years ago, I've made a list of these programs.
To get the best security programs, often you will have to pay but there are however many very good and some excellent programs available for free.

Almost all programs listed are available for XP, Vista and Win7 (not all programs support 64-bit versions).
These are all free programs, not limited trial versions.

It's not necessary to choose one program from every section.
Rather than piling security programs, common sense, backups/images and a limited/standard user account for daily work is much more important. (The list is updated regularly).

Anti Virus
Avast! Free Antivirus 7.0......98,0% - 14 FP
Avira AntiVir Personal 12......99,4% - 15 FP (includes 3rd party advertising)
MSE 4.0........................... 93,1% - 0 FP (create a (daily) update task)
Panda Cloud Antivirus 1.5......98.6% - 10 FP

The detection %-scores and number of 'False positives' are from the AV-Comparatives March 2012 'on-demand' test.
(These are not on-execution/behavioural detection scores).
Test results, test methods and real world/dynamic test results, can be found here.
N.B. These scores are achieved with the highest settings.

Firewall + HIPS
Comodo CIS 5............. XP/Vista/7-32&64
Online Armor 5 ............XP/Vista/7-32&64
PC Tools Firewall Plus 7.. XP-32, Vista/7-32&64

Comodo Firewall Pro and it's HIPS 'Defense+', can be installed without the antivirus in CIS/Comodo Internet Suite.
Make sure to read a user guide before setting up a HIPS (if applicable); CIS pdf, OA, PCTF+

Anti Spyware/Malware
Dr. Web CureIt!..................scan and clean program for infected systems
HitmanPro 3.....................fast antimalware scanner (combined engines from, Avast, BitDefender, Dr. Web, Emsisoft and Ikarus, details here)
MalwarebytesAntiMalware..on-demand scanner
SpyWareBlaster..................blocks websites known for spyware
SuperAntiSpyware..............on-demand scanner

Miscellaneous free security programs
EMET 3.0...........................Microsoft's exploit prevention program
GesWall............................Intrusion Prevention Sytem
NoScript ............................Firefox add-on; disable Java, Flash, I-Frame, WebGL, protect against XSS/XSRF, clickjacking
Prevx SafeOnline..............Browser protection; harden your internet banking/https traffic (IE, FF, Chrome & Opera)
Returnil Virtual System......create a temporary virtual version of your OS and programs to prevent malware in the real OS
Sandboxie........................run internet-facing programs in an isolated secure space, preventing changes to your OS, programs and data.
Secunia OSI.....................online scan to find updates and patches for most common programs in order to avoid possible exploits.
WinPatrol.........................system monitor

Online Virus/Spyware/Malware scanners
Bitdefender Online Scanner
Dr.Web Online VirusScan....for individual files
Eset Online Scanner
F-Secure Online Scanner
Jotti Malware scan.............for individual files up to 25MB, combining over 20 av/am scanners
VirusTotal.........................for individual files up to 32MB, combining over 30 av/am scanners
Metascan Online................for individual files up to 40MB, combining over 18 av/am scanners

Online Firewall Tests......test if your ports are blocked /stealthed but read this also
AuditmyPC
Comodo free scan
Hackerwatch.org
PC Flank
Shields Up/GRC

Not sure about these programs?
Then check these independent sites for comparisons and information.
AV Comparatives - Antivirus tests, though not for all the free versions.
AV-Test - Antivirus & security suites tests
Wilders Security - One of the best sites/fora, dedicated to security software.

[Johnny T]

Also Spybot Search and destroy is a big one you forgot as well

[Calvin]

Are you sure about avg anti-spyware? It's not free and even though it's from avg it doesn't look too good.

[Calvin]

Also, you might want to add stuff like "(very recommended)" next to ones like spybot and antivir.

[Hiker]

How about Adaware 2007?

[Tranquility]

It may be more than you wanted to get into, but a note about using a limited user account is at least a good idea. They are free and can probably do as much, if not more, than all of those programs combined when it comes to prevention.

[The Forerunner]

Sticky please!

[Thibault]

Like Hiker already mentioned, you forgot about Lavasoft Ad-Aware. They offer a free version of their product.

Also, I thought that avast! offered a free version of their anti-virus?

Very good topic, by the way.
You could also add a section for a list of free registry cleaners (like CCleaner).

[Thibault]

Originally Posted by Baserk

Ad Aware 2007 is added.
For AdAware 2008, it's a bit too early
Avast was already in the list.
I like CCleaner myself but I don't know much more comparable programs.
Registry Mechanic is good but the free version only deletes 5 reg values per run.
Advice for more good free registry cleaners to make a decent list is very welcome.

Oh so it is. I read through the list and didn't remember avast being there.
Well that's all I can think of, and if people know of a few free registry cleaners you could add a list for it. I agree that right now there isn't much a point so I only really know of CCleaner.

[Padmé]

Originally Posted by Baserk

Calvin, I'm afraid your right, after the 30 day trial period most features are disabled.
It turns into freeware without the features that make it usefull.
If it can only detect but not remove spyware it becomes pretty much useless.
My bad, I will remove it from the list as the full program is NOT free.

The only thing that I know of that's disabled in the free version is the resident shield. I've been using it since before AVG bought out the other company that had it. I can't recall the name of that company at the moment. It's worked pretty well for me, though.