XP has been around since 2001, which means that you've really had more than enough time to let it go. But you're not the only one. A number of businesses, not to mention governments, still rely on XP-based systems. The Dutch and U.K. governments, for example, paid Microsoft a few million dollars to extend support for a year, The Guardian reported.

What happens for those who don't upgrade? Well, if any bugs are found after Tuesday, Microsoft won't be fixing them, though it will support antimalware signatures for XP through July 14, 2015. There's also the fact that you're running a 13-year-old OS so you'd likely see better performance if you upgrade. That is, if your system can handle it. How do you know?

At its recent Build conference, Microsoft lowered the system requirements for Windows 8.1 so more machines can upgrade to the latest OS.