Steps to take before you install Windows XP Service Pack 3
http://support.microsoft.com/kb/950717

 

SP3 Installation Guide
http://technet.microsoft.com/en-us/windowsxp/cc164204.aspx

 

IE Browser Versions and Windows XP Service Pack 3
http://blogs.msdn.com/ie/archive/2008/05/05/ie-and-xpsp3.aspx

 

How to troubleshoot an unsuccessful installation of Windows XP Service Pack 3
http://support.microsoft.com/kb/950718

 

The Address toolbar no longer appears on the taskbar after you install Windows XP Service Pack 3
http://support.microsoft.com/kb/951448

 

Free unlimited installation and compatibility support for Windows XP ServicePack 3 (until April 14/09)
http://support.microsoft.com/oas/default.aspx?ln=en-us&prid=11273&gprid=522131

 

Troubleshooting error codes/messages
http://support.microsoft.com/kb/950717/  (bottom of page)

 

XP SP3: Problems? How To Uninstall Service Pack 3
http://aumha.net/viewtopic.php?f=62&t=33246

 

I realise some of these links were previously posted, but thought this collection might be of assistance. Feel free to add any other useful SP3 links.