Microsoft Support for Windows Vista (with no service packs installed) ended on April 13, 2010, while support for Windows XP (without Service Pack 3 installed) ended on July 13, 2010. Windows 2000 support ended on July 13, 2010 as well.
There is no Service Pack 3 for the 64-bit version of Windows XP. If you're running the 64-bit version of Windows XP with SP2, you have the latest service pack and will continue to be eligible for support and receive updates until April 8, 2014.
If you are still running a version of Windows where support has ended, it means that version of Windows will no longer receive any updates from the Windows Update or Microsoft Update site. These updates are generally provided for security reasons to help protect the PC from harmful viruses, spyware, malware, and other malicious software. Windows Update also provides new drivers for your hardware that can improve the reliability of Windows.
Hackers love to take a security vulnerability in Windows and exploit it to their advantage. So, if a vulnerability is found in Windows XP or Windows Vista and you are not running the latest service pack, you will not be protected and will be at risk. How Can I Tell What Service Pack is Installed?
Follow these steps to discover what Service Pack is installed:
1) Click on the Start Button
2) Right-click on either My Computer or Computer (depending on your Windows version)
3) Click on Properties
On this window, it should tell you which version of Windows along with which service pack is installed). It should also tell you whether you are running a 32 bit or 64 bit version of Windows. Where can I download the latest Service Pack for Windows?
For Windows XP, click on the following link to download Service Pack 3
For Windows XP Service Pack 3 info, click below :-http://windows.microsoft.com/en-us/windows/help/learn-how-to-install-windows-xp-service-pack-3-sp3
For Windows XP Service Pack 3 download, click below :-http://www.microsoft.com/downloads/details.aspx?FamilyId=5B33B5A8-5E76-401F-BE08-1E1555D4F3D4
For Windows Vista, click on the following link to download Service Pack 2
Windows Vista Service Pack 2 info, click below :-http://windows.microsoft.com/en-us/windows-vista/Learn-how-to-install-Windows-Vista-Service-Pack-2-SP2
Windows Vista Service Pack 2 download, click below :-http://support.microsoft.com/kb/935791