Both answers given say it, but I don't consider them clear enough. This lead me to add an answer of my own, just to clarify things.
Microsoft stopped providing updates for Windows XP since april 1st 2014. The updates excluded are
security hotfixes for Windows XP and
updates to Microsoft Security Essentials.
The Windows Update functionality won't stop, but no updates that fix security leaks in Windows XP will be patched, meaning that the longer you use Windows XP the bigger the chances are that your pc becomes infected with spyware and a hacker can take over your pc installing randsomware and other crap.
Especially old pc's had a problem because updating to a newer OS meant that it just would not be possible due to the performance. Luckily, since the recent Windows 8.1 update, if you install Windows 8.1 32 bit (given that you have less than 4 GB of ram) it will actually perform better than Windows XP will. I experienced this first hand myself when I was forced to update my old pc. Not to mention that a full install of Windows 8.1 requires less free diskspace than Windows XP does.