(Update: Microsoft has now announced that it will at least maintain Microsoft Security Esssentials AV to July 2015: Click for details. Otherwise there will be no support after April 2014.)
Windows XP will no longer be supported by Microsoft after April.
That means you need to quit using it online. It will NOT be safe to use Windows online securely.
So what are your options?
Disconnect your XP device from internet in any event when the time comes.
It may be that your old device may be upgradeable to Windows 7 or 8 and 8.1. Install Windows Upgrade Assistants to find out if Microsoft thinks so. Then, take that with a grain of salt. OK to try only if you are a tinkerer.
You nay be able to find a tutorial for your specific old machine on YouTube. You may be able to boost memory and speed cheaply with ReadyBoost. Click here to read about ReadyBoost. I also found a cheap RAM upgrade for my old antique.
Better, you may be able to install a free Windows look alike like Zorin Ubuntu Linux software, also available online. Search for Zorin. Not a bad solution if money is short.
It will be more practical just to buy a new computer. That could cost as little as $300. A little tweaking will help it run like a champ.* This the best option.
That new computer will have Windows 8 or 8 .1, which requires some learning to use, like it or not.
To transition, files and apps need to be provided for. Establish Dropbox on your older computer if necessary to hold them, back them up, and access them from the new computer and anywhere else.
That will leave many users between a rock and a hard place. In other words, the old computer will not be upgradeable and the new Windows 8 computer undesirable or even incompatible with your old devices and software.
Fortunately there are plenty of tablets out there which will do most of the things seniors need to do. They are far more intuitive and reliable than older systems. Most of these will actually run Microsoft Office Suite, such as through Skydrive, plus many other alternative office packages. Simplest, download and install Open Office. Use a fast browser like Opera.
Your choice. XP will no longer be secure.
Dump it, probably along with your old machine.
* Note: Running one app at a time and using cloud storage and apps will help any computer run better, old or new.