New Features in XP SP3 For the most part, Microsoft is doing their best to avoid pulling Vista features into XP, with just a few exceptions. They are:
Network Access Protection (NAP): A new system in Vista and Windows Server 2008, this feature sets system "health" requirements to validate a computer's health before it allows that computer to connect to yours.
"Black Hole" Router Detection: This new feature detects when your router is silently losing or discarding packets and is intended to protect from such problems.
Product Activation Not Required on Installation: Like Vista, you can now install XP without first providing a valid product key. Windows will prompt for a product key after installation, though, if you want to take advantage of Windows Genuine Advantage.
Kernel Mode Cryptographic Module: In a nutshell, this Vista back-port makes it easier to encrypt data through a single algorithm. Enjoy that one!
Aside from these Vista back-port features, other new features include more descriptive security options that better explain your security settings and improved administrator security
Official Windows XP Service Pack 3 Full Download Links : 316.43 MB