Microsoft shutdown the security and other updates for windows XP that could make your PC unsecured and you might need to run XP application or software. You can still run windows XP and its application in your windows 7 or 8 by installing virtual Windows XP with VirtualXP application.
VirtualXp software install the Windows XP under your windows as application and you can run it when you want or open at start up according to your needs. Its free but you can buy its license for support and some premium features.
You can download VirtualXP from here for free and if you need more windows tips go here.