After 12 years Microsoft has stopped provide support for Windows XP and from April 8 technical assistance for Windows XP is no longer available, also including automatic updates for viruses.
Microsoft Security Essentials is not longer available for download, although you will continue to receive antimalware signature updates for a limited time, if you have it already installed.
This means that your pc is more vulnerable to security risks and viruses.
What can you do?
The first thing is to check if your PC meets the system requirements (processor, RAM memory, hard disk space and graphics memory) in order to update to Windows 8.1.
Download the Windows Upgrade Assistant and, if the system requirements are correct, follow the steps to begin the upgrade.
And if your PC can’t run Windows 8.1?
You only have two options:
1) Run a open source operating system based on Linux , such as Ubuntu
2) Consider to buy a new PC