As others have mentioned, your copy of XP will continue to work, it does not mean that your PC will no longer bootup to XP.
The only thing it means is MS is no longer paying folks to research, find and fix broken things in the XP OS.
What this means to you is they are no longer dedicating manpower or time to find all those really obscure security risks which may be leftover.
The good news though is XP in its final form of SP3 is very mature which means it is stable.
The downside is if a hacker is willing to put in years of messing around with XP they "could" find one of the obscure never found security risks..
Over all you should be fine as long as your PC does not have a hardware failure or you get hit by malware or a virus..
I myself am going to continue to use my XP PCs until the hardware gives out and even then I have a legal copy of W7 to install on a new system board in the future (I bought a W7 copy before they disappear).
Do make backup copies of your important files as a just in case thing.