The recent Microsoft announcement about support ending for Windows XP may have generated some confusion.
Here is how I understand it.
If you have Windows 2000, support will end July 12, 2010.
If you have Windows Vistas WITH NO SERVICE PACKS INSTALLED, support will end April 13, 2010. You should install service packs 1 and 2
If you have Windows XP WITH SERVICE PACK 1 OR 2, support will end July 12, 2010. You can extend that by installing seervice pack 3 for XP.
End of support means that Microsoft will not longer fix bugs in these versions. Importantly this means no more security patches.
TechMan's recommendation for XP users is to upgrade to Windows 7. Even XP SP3 with support is not a secure OS. However, if you like XP, you can hang on a little longer by installing service pack 3.
Instructions for getting service pack 3 are here: http://support.microsoft.com/kb/322389
To find out if you have service pake 3, go to start, settings, control panel, system, general tab