Windows XP is dead - long live XP
If you still running Windows XP it is time you stopped
.... you are almost alone.
The most immediate task for you is to stop using Internet Explorer and move up to Firefox, until May 2018 security updates will continue to be provided, but it is an older version than on later Windows versions. Microsoft refuses to allow the new versions of IE to be installed on XP. The good news is that Firefox is better than your version of IE, and is fully patched and up to date, sadly Chrome is no longer up to date and will never be updated, it is still better than IE, but not for long.
There are no more updates, so turn off Windows Update, as a by-product you won't get nagged by Micro$oft to upgrade.
If you are running Microsoft Security Essentials, stop it!! Download the free Avast Antivirus and if you want a greater level of protection then pay the small asking price to get additional protection - much better than anything Microsoft ever offered. Virus definitions and updates stopped long ago for Microsoft Security.
Now the bigger problem.......
Windows XP will continue to function as long as you want it, and I will be available to fix it for as long as you want me to. You should be aware that there are flaws in your operating system that may make it vulnerable to some forms of attack from the internet - these are not new, they have always been there, it's just that no-one cares to try fix them any more :-(