Differences Between SP2 & SP3

# Microsoft's Windows XP operating system contains three service packs released over the past several years. While the first service pack provided minor updates to the operating system, the second and third releases provided updates for users who do not want to switch to a new Windows system. Service Pack 3, released in 2008, updates 2004's Service Pack 2.
Overview of Windows XP
# Microsoft released the Windows XP operating system in October 2001. Windows XP provided upgrades from its Windows 2000 and Windows Millennium Edition software. These upgrades included faster start-up times, increased support for hardware drivers and remote desktop functionality, which allowed users to access their computer from other locations. Despite Windows releasing two subsequent operating systems, Windows XP is still the most widely used operating system in the world.
Service Pack 2
# Windows released its second service pack for Windows XP in 2004. In addition to including all previously released updates, Service Pack 2 included new features including Windows Firewall, Security Center and Windows Media Player 9. Microsoft also included security updates for Outlook Express and Windows Messenger, its e-mail and instant-messaging programs. Many of the security features are used in subsequent Windows releases.
Service Pack 3
# Microsoft released its third and final service pack for Windows XP in 2008. Microsoft originally planned to release Service Pack 3 several years before, but the development and release was delayed due to Microsoft preparing its new Windows Vista system. Service Pack 3 is the final major update for the Windows XP operating system. However, Microsoft recently announced that it will continue to offer support and security updates for XP systems running Service Pack 3 until 2014.
Enhanced features
# In addition to adding new features, Microsoft's Service Pack 3 included updates to features from Service Pack 2. One such update is Windows Installer 3.1. This update corrects several issues from Windows Installer 3.0, such as fixing the progress bar during installation and allowing patching of isolated files. Service Pack 3 also included Remote Desktop 6.1, which allows people with XP computers the ability to connect to computers running Windows Vista. It also includes support for the Wi-Fi Access 2 security standard, a standard previously unsupported by XP.
New Features
# Service Pack 3 also included several new features. One such feature is an improved security control panel. The new panel includes more-descriptive text to explain settings. This helps keep users from selecting incorrect security settings for their computers. Another new feature is no-key installation. This allows users to install XP with Service Pack 3 without needing a registration key. Service Pack 3 also now turns on black hole router detection by default. Black hole routers silently discard information packets, leading to information being lost in transmission.