Download – The RC can be downloaded as a stand alone package (336MB) from http://www.microsoft.com/downloads/details.aspx?FamilyId=75ED934C-8423-4386-AD98-36B124A720AA&displaylang=en. RTM release will also be available via Windows Update.
Overview – http://www.microsoft.com/downloads/details.aspx?FamilyID=68c48dad-bc34-40be-8d85-6bb4f56f5110&DisplayLang=en
KB Article – http://support.microsoft.com/?kbid=936929
Deployment – Windows XP SP3 is for x86 editions of Windows XP only. The x64 editions of Windows XP were serviced by Windows Server 2003 SP2. Windows XP SP3 is cumulative, so users can install SP3 on top of Windows XP SP1 or SP2. Windows XP SP3 supports the same languages as Windows XP did in its initial release. Windows XP SP3 does not include Windows Internet Explorer 7.
New Technologies – "Black Hole" Router Detection, Network Access Protection (NAP) client.
Updated (or previously stand-alone) Technologies – MMC 3.0, MSXML6, Microsoft Windows Installer 3.1 v2, Background Intelligent Transfer Service (BITS) 2.5, IPsec Simple Policy Update for Windows Server 2003 and Windows XP, Digital Identity Management Service (DIMS), Peer Name Resolution Protocol (PNRP) 2.1, Wi-Fi Protected Access 2 (WPA2).
I took this from the Nick MacKechnie blog...