The support for Windows XP will end as communicated by Microsoft on April 8th, 2014.
A spokesperson issued the following statement to Larry Seltzer of ZDNet:
Microsoft will not guarantee updates of our antimalware signature and engine after the XP end of support date of April 8, 2014.[...]
What does this mean for the XP users?
The free Microsoft Security Essentials is no longer going to protect the users with new signatures. It is still unknown how exactly will the product react, but most probably it will simply remain for ever up to date. This is the worse scenario actually, because the user will not be aware that he is using an outdated antivirus product.
What is the alternative?
The best alternative is, of course, Avira Free Antivirus which continues to be supported by Avira one year after the main stream support offered by Microsoft for the operating system ends. Avira Free Antivirus runs on Windows XP SP3 (32-bit), Windows XP SP2 (64-bit) and requires a computer with minumum 1 GB RAM (2 GB recommended).
Do not forget that the best way to stay away from troubles is to have up to date software, especially an up to date operating system. Unfortunately, since Microsoft will not patch security vulnerabilities of XP anymore, there will be other problems arising. Malware authors will target more and more from now on this operating system, knowing that any vulnerability they find will remain there for good. This is why we strongly recommend to migrate from XP as soon as possible.
But, as long as you are stuck on XP because of legacy software, you can count on any Avira product to protect you.