When you change the system state by adding, changing, or removing Windows XP components, you DO NOT have to reinstall the service pack.
When you install a Windows XP service pack, the Update.exe program:
- Updates the Layout.inf file with the location of the service pack files. This causes system state changes to point to the correct source files.
- Stores the source location at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\ServicePackSourcePath. The ServicePackSourcePath can be a network share, the Windows XP service pack CD-ROM, or, if you performed an Express Installation from the Web, the %SystemRoot%\Servicepackfiles folder. See tip 5722 » When you add Windows component to Windows XP with SP1 installed, setup prompts you for the SP1 CD-ROM or the I386 folder?.
- Updates the Drvindex.inf file to point to the additional SPn.CAB file in the %SystemRoot%\Driver Cache\I386 folder. The service pack SPn.CAB file replaces any hotfix SPn.CAB file. A new SPn.CAT file is installed in the %SystemRoot%\System32\CatRoot\\{F750E6C3-38EE-11D1-85E5-00C04FC295EE\} folder.
- Performs version checking on files so that post Windows XP SPn hotfix files remain in place. You DO NOT have to reinstall the post Windows XP SPn hotfixes.
NOTE: Pre SPn Hotfix files that you installed prior the installing the service pack are updated by the service pack.
NOTE: When you install a hotfix, the Layout.inf file is NOT updated. If you make a system state change after applying a post Windows XP SPn hotfix, you should reinstall the hotfix, until you install service pack n+1.
