As of April 8, 2014 Microsoft stopped supporting Windows XP and therefore it is no longer an officially supported platform. Users may still continue to use Java 7 updates on Windows XP at their own risk, but we can no longer provide complete guarantees for Java on Windows XP, since the OS is no longer being updated by Microsoft. We strongly recommend that users upgrade to a newer version of Windows that is still supported by Microsoft in order to maintain a stable and secure environment.
We expect that Java 7 (and older versions) will continue to work on Windows XP.
Yes, Security updates issued by Oracle will continue to be pushed out to Windows XP desktops at least until the End of Public Updates for Java 7 which is currently scheduled for April 2015 (Java Support Roadmap). Users that download Java 7 from java.oracle.com or java.com will continue to be able to install on Windows XP.
We will continue to monitor the uptake of Java 7 updates on Windows XP. If usage remains high when we get close to that milestone, we will take measures to keep Java users safe.
Java 8 is not supported on Windows XP, and Windows XP users will be unable to install Java 8 on their systems as there are known issues with the installer on Windows XP that prevent it from installing without manual intervention. If you are on Windows XP it is not clear that it is worth updating to Java 8 without also updating the OS.
Customers with a support contract may be required to reproduce an issue encountered on Windows XP on a later version of Windows, and if the issue is specific to Windows XP Oracle is not required to (and may be unable to) issue a patch or a workaround. See Third Party Vendor-Specific Support Terms on Oracle Software Technical Support Policies (pdf) for details.