The best free security software

"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, sometimes you will have to pay but there are 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 using a limited/standard user account for daily work are much more important.
Use only what you master and keep the OS and programs updated. And again, backup!

Anti Virus
Avast! Free AV 7........98,6% - 11 FP
Avira Free 2013..........99,8% - 10 FP (includes 3rd party advertising, scores are for Avira 2012)
MSE 4.0....................94,9% - 0 FP (create custom/regular update task)
Panda Cloud AV 2.0....99.6% - 20 FP

The detection %-scores and number of 'False positives' are from the AV-Comparatives Sept 2012 file-detection test link.
(These are not on-execution/behavioural detection scores. Avira scores are achieved with high heuristic settings).
Paid AV and full security suites (and some free version) test results are available at AV-Comparatives ongoing real world/dynamic detection test results link,
Also bi-monthly 'detection, repair & usability' test results at AV-TEST.org link, daily&small sample set zero-day malware test results from MRG Effitas link and free AV real-time test results at WestCoastLabs.com link.


Firewall + HIPS
Comodo CIS............. XP/Vista/7-32&64
Online Armor ............XP/Vista/7-32&64
PrivateFirewall......... 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, PFW pdf

Anti Malware
Dr. Web CureIt!..................scan and clean program for infected systems
Emsisoft Emergency Kit.....portable (USB) malware scanner
HitmanPro 3.....................fast antimalware scanner (combined detection from, Avast, BitDefender, Dr. Web and Emsisoft, details here)
MalwarebytesAntiMalware..on-demand scanner
SpyWareBlaster..................blocks websites known for spyware

Miscellaneous free security programs
EMET 3.0...........................Microsoft exploit prevention program
GesWall............................Intrusion Prevention Sytem
JavaRa..............................Update Java and remove any old leaky versions.
NoScript ............................Firefox add-on; disable Java, Flash, I-Frame, WebGL, protect against XSS/CSRF, 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 PSI 3.0..................Automatically 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
....[/COLOR]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.

(Post updates discontinued Nov 2012)

 

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

 

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

 

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

 

How about Adaware 2007?

 

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.

 

Sticky please!

 

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).

 

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.

 

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.