If you are not aware of Microsoft Security Essentials (MSE), it is Microsoft's free antivirus / antispyware program for Windows.
Malware is a big problem, especially for Windows users and the very fact that Microsoft felt the need to publish such a program indicates their ever growing concerns.
However I feel this slap in the face approach by Microsoft is a bit of a gimmick.
Windows by design has made it easy for viruses to run and compromise a system, so instead of wasting time on an antivirus program Microsoft need to wake up and sort the problem where it fundamentally lies, the operating system itself.
Those who enthusiastically support Microsoft may feel the need to stress that the way you use your PC has a direct relation to security.
A user's surfing habits and other activities such as downloading torrents and using p2p programs influence the risk of infecting your PC.
But if you do the same on a Linux based operating system there is no risk, therefore I do not buy the user is the problem reply.
Others may like to shout, as long as you have a good antivirus which is kept up to date you are safe from online threats.
I say to those who believe this, you are living in cookoo land.
In simple terms, an antivirus program scans a file and compares it to a list called the virus definition database, if a match occurs a detection occurs.
Now pay attention because here is the biggest flaw of all antivirus programs.
If it isn't on the list a detection cannot occur, hence a virus can run without your knowledge.
That is just the icing on the cake, the real underlying issue and downfall that antivirus vendors face concerns the addition of a new and unknown virus samples to their detection list.
If they are not aware of a new and unknown virus, it will never be added to their detection list and as a result it will never be detected by their antivirus program.
In other words antivirus vendors are playing a losing game, they are always behind and it is a dangerous misconception to believe as a user you are safe from threats as long as you have an up to date reputable antivirus software.
Yes you are safer but you can never be 100% safe.
Methods such as heuristic and generic detection work on the basis that traces of a known virus signature or certain coding techniques are present.
Therefore these also will never be able to detect new and unknown viruses and often cause unreliable results, ie false detections.
I remember an incident many years ago with my then ISP, Blueyonder. They used Kaspersky on their pop3 email servers. One day I received another junk email that contained an attachment. Being the sensible user, I did not open the attachment.
My antivirus at the time (Avast Home Edition) didn't detect anything.
Submitting the file for further analysis to http://virusscan.jotti.org/en-gb, revealed the detection of a virus.
To put this into perspective, a virus was delivered to my system which both Kaspersky and Avast failed to detect.
I then went into a paranoid state, running a full system scan with Avast, Spybot and an online scan using http://housecall.trendmicro.com/uk/
Upon reflection, I find this quite funny...
Back to Microsoft Security Essentials, it is a piece of trash because it causes too much disk activity.
Having installed it on my Laptop I noticed a sharp decrease in battery life and after some time I was able to pin point the culprit, MSE.
Trying MSE on my Desktop PC also resulted in excessive disk activity and the performance degradation was visibly noticeable.
Opening folders and running programs were taking longer to load.
Furthermore when opening a folder containing a quantity of various *.exe, *.zip and *.iso files, the apparent and immediate delay is quite shocking.
I expect better from Microsoft, they have done a “Vista” with MSE.
Other free antivirus programs by AVG, Avast and Avira perform much better and cause an acceptable performance hit.
I haven't tried MSE recently, perhaps it has changed and improved?
If you are interested in much better alternatives to MSE, here are the 3 most popular free antivirus programs in no particular order,
Avast Free: http://www.avast.com/en-gb/index
AVG Free: http://free.avg.com/gb-en/homepage
Avira AntiVir Free: http://www.free-av.com/