Windows XP has been around for over a decade now and I am fairly certain that many farmers are still using this as their desktop operating system. Microsoft only officially supported this software until April 8, 2014. After that date, they will stop updating the software for any new viruses, malware or other items that may affect proper use of the software.
If you are still using this as your primary operating system, I would highly suggest upgrading to a new operating system. Here is a very good summary of the issues surrounding the expiration of Microsoft's support. I think you may find it helpful. As a side note, the IRS still uses Microsoft XP on many of their computers.