The folks over at Neosmart have written a small analysis of the upcoming SP3. According to their analysis, most of the changes are OS-deep, so from a aesthetic perspective, you probably wont notice anything. Right now SP3 is a collection of Windows XP bugfixes and a few backported functions that Vista has.

• New Windows Product Activation model: no need to enter product key during setup. Thank God for that!
• Network Access Protection modules and policies have been brought to XP after being one of the more-well-received features in Windows Vista. You can read more about NAP here.
• New Microsoft Kernel Mode Cryptographic Module - the Windows XP SP3 kernel now includes an entire module that provides easy access to multiple cryptographic algorithms and is available for use in kernel-mode drivers and services.
• New “Black Hole Router” detection - Windows XP SP3 can detect and protect against rogue routers that are discarding data.

At least security-wise, looks like XP users will be alright until Vista becomes usable, or if it’s upcoming SP1 is as good as some people have been reporting. I just hope that they manage to fix the installation issues that some users have been experiencing when they try out SP3.