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 8 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Windows XP at their own risk, but we can no longer provide complete guarantees for Java on Windows XP, since the OS is no longer being updated by Microsoft.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 8 (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.
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.