Windows XP is just being desupported. Desupported means that if any new bugs or issues with the software are found, that they won't be fixed. Also, software developers will not test new software or upgrades on it, so over time, you will find it harder and harder to get programs you may want, etc.
Your computer is likely to run just fine for quite awhile yet. But since your computer is running Windows XP, your hardware is probably also older (in relative computer terms) so it is most likely slower, has less memory, has less disk space, etc. If you feel like performance is an issue for you, then I would start watching for a good deal on a new system and not invest any money in repairing your existing system should something break - but I wouldn't run out and buy something today, just wait for a deal that's too good to pass up. If you feel performance is not an issue on your current system, then you should consider upgrading to Windows 8 - AFTER you carefully check the system requirements to make sure your system is capable of running it effectively. The increased disk space and memory requirements may push a system that runs well now over the edge so it is a dog after the upgrade.