Microsoft has announced the Windows XP end of support date of April 8, 2014. After this date, Windows XP will no longer be a supported operating system. To help organizations complete their migrations, Microsoft will continue to provide updates to our antimalware signatures and engine for Windows XP users through July 14, 2015.
This does not affect the end-of-support date of Windows XP, or the supportability of Windows XP for other Microsoft products, which deliver and apply those signatures.
For enterprise customers, this applies to System Center Endpoint Protection, Forefront Client Security, Forefront Endpoint Protection and Windows Intune running on Windows XP. For consumers, this applies to Microsoft Security Essentials.
Our research shows that the effectiveness of antimalware solutions on out-of-support operating systems is limited. Running a well-protected solution starts with using modern software and hardware designed to help protect against today’s threat landscape.
Microsoft recommends best practices to protect your PC such as:
• Using modern software that has advanced security technologies and is supported with regular security updates,
• Regularly applying security updates for all software installed,
• Running up-to-date anti-virus software.
Our goal is to provide great antimalware solutions for our consumer and business customers. We will continue to work with our customers and partners in doing so, and help our customers complete their migrations as Windows XP end of life approaches.
MMPC
Source: Microsoft antimalware support for Windows XP - Microsoft Malware Protection Center - Site Home - TechNet Blogs