"To aid IT professionals in planning and testing for the deployment of Windows XP Service Pack 2 (SP2), Microsoft is making available this preview, based on Release Candidate 2 (RC2) of SP2. Additionally, we have established 11 newsgroups for sharing information."

Go on, you know you want to! Trash your Windows install in one easy step with this download.

Windows XP SP2 RC2 Express Installer (via Windowsupdate).

Windows XP SP2 RC2 Network Installation.

View Release Notes and Information.

More here. Official Microsoft Technet article here.