Serive Pack contain security updates, hotfixes, improvements/added funcionalities and other updates for Windows XP.
There are 3 SP for XP:
Service Pack 1
It contains post-RTM security fixes and hot-fixes, compatibility updates, optional .NET Framework support, enabling technologies for new devices such as Tablet PCs, and a new Windows Messenger 4.7 version. The most notable new features were USB 2.0 support and a Set Program Access and Defaults utility that aimed at hiding various middleware products. Users can control the default application for activities such as web browsing and instant messaging, as well as hide access to some of Microsoft's bundled programs. This utility was first brought into the older Windows 2000 operating system with its Service Pack 3. This Service Pack supported SATA and hard drives that were larger than 137GB (48-bit LBA support) by default. The Microsoft Java Virtual Machine, which was not in the RTM version, appeared in this Service Pack.[39] Support for IPv6 was also introduced in this Service Pack.
Service Pack 2
Unlike the previous service pack, SP2 added new functionality to Windows XP, such as WPA encryption compatibility and improved Wi-Fi support (with a wizard utility), a pop-up ad blocker for Internet Explorer 6, and Bluetooth support. The new welcome screen during the kernel boot removes the subtitles "Professional", "Home Edition" and "Embedded" since Microsoft introduced new Windows XP editions prior to the release of SP2. The green loading bar in Home Edition and the yellow one in Embedded were replaced with the blue bar, seen in Professional and other versions of Windows XP, making the boot-screen of operating systems resemble each other. Colors in other areas, such as Control Panel and the Help and Support tool, remained as before.
Service Pack 2 also added new security enhancements, which included a major revision to the included firewall that was renamed to Windows Firewall and became enabled by default, Data Execution Prevention, which can be weakly emulated,[clarification needed] gains hardware support in the NX bit that can stop some forms of buffer overflow attacks. Also raw socket support is removed (which supposedly limits the damage done by zombie machines). Additionally, security-related improvements were made to e-mail and web browsing. Windows XP Service Pack 2 includes the Windows Security Center, which provides a general overview of security on the system, including the state of antivirus software, Windows Update, and the new Windows Firewall. Third-party anti-virus and firewall applications can interface with the new Security Center.
Service Pack 3
Windows XP Service Pack 3 (SP3) was released to manufacturing on April 21, 2008, and to the public via both the Microsoft Download Center and Windows Update on May 6, 2008.[47][48][49][50]
It began being automatically pushed out to Automatic Update users on July 10, 2008.[51] A feature set overview which details new features available separately as standalone updates to Windows XP, as well as backported features from Windows Vista has been posted by Microsoft.[52] A total of 1,174 fixes have been included in SP3.[53] Service Pack 3 can be installed on systems with Internet Explorer versions 6, 7 or 8.[54] Internet Explorer 7 and 8 are not included as part of SP3.[55]
[edit] New features in Service Pack 3
* Turns black hole router detection on by default[56]
* Network Access Protection client
* Group Policy support for IEEE 802.1X authentication for wired network adapters.[57]
* Credentials Security Service Provider[58]
* Descriptive Security options in Group Policy/Local Security Policy user interface
* An updated version of the Microsoft Enhanced Cryptographic Provider Module (RSAENH) that is FIPS 140-2 certified (SHA-256, SHA-384 and SHA-512 algorithms)[56]
* Installing without requiring a product key during setup for retail and OEM versions
[edit] Previously released updates
Service Pack 3 also incorporated several previously released key updates for Windows XP, which were not included up to SP2 including:
* Windows Imaging Component[59]
* IPSec Simple Policy Update for simplified creation and maintenance of IPSec filters[60]
* Background Intelligent Transfer Service (BITS) 2.5
* MSXML 6.0 SP2 and XMLLite
* Microsoft Management Console 3.0
* Credential Roaming service (Digital Identity Management Service) update
* Remote Desktop Protocol 6.1
* Peer Name Resolution Protocol 2.1
* Network Diagnostics update
* WPA2 Update (KB893357)
* Windows Script 5.7
* Windows Installer 3.1 v2