So what does it mean to the ordinary Windows XP user, well Microsoft will not release any security updates after 8th April 2014.  Which leaves the computer systems exposed to all sort of malicious attack.
Microsoft solution is to migrate to Windows 8.1 Update click the link to see IT Pro Perspective on the new update. There is a lot more for the end user that will keep you glued and as you discover some of these things you will start to love and understand the modern OS. Power User can look at the features that are available with the new Windows 8.1 update 1.

For those who are going to be stuck on using Windows XP there are few things you should try to make your environment more secure.
1. Check the version of Windows XP that is currently running on your system. Click Start -> Run-> type WinVer->click ok
you are looking Windows XP version 5.1 with Service Pack 3

2. If by some chance your system is not up to date you can still go to Windows Update and get the current available system updates. In an enterprise environment use the Windows Server Update Services. As you want to keep the machines away from the internet till they are protected.

3. Make sure you have the latest available web browser, Internet Explorer 8, chrome, safari, or firefox. All should be able to give you some protection against malware.

4.If you have apps that are old and unnecessary (hording is your worst enemy at this point) remove them, there several tools that can be able to assist with removal ccleaner and revo uninstaller are both compatible with Windows XP and will do a good job for you.

5. Securing the working environment is one thing , also remember to ensure that the Applications running in that system are up to date. You can download tools that help you to maintain updated apps softonic for Windows XP

6. Install and antivirus software there several good free providers like avira, smadav or get Microsoft's security-essentials-all-versions

7. Installing a firewall in your network will help you to monitor your network traffic and ensure that you can block unwanted sites. Also try to remove any programs that unnecessary from startup Click Start -> Run-> type MSCONFIG->click ok on the tabs select Start Up remove the check on the apps you do not want to startup automatically.

8. Avoid using Outlook Express/live mail as these will not protect your emails and your system from phishing mail and programs. You can use alternate mail services Outlook.com is a very good one

9. Backing up of the system and the data will save you tears when you are attacked so create a backup plan and automate the process.

10. If your reason for not migrating to the modern operating system is compatibility of legacy applications to the new OS. You can virtualize these apps and run them from a virtual environment as and when you need them.

Thank you @remoquete, Ben Hunter and @WinBetaDotOrg