As stated, the alterations that Windows XP's third service pack brings to the game are background improvements. While some of them are more noticeable than others, the user won't actually see or "feel" any changes in the graphical user interface (GUI). The experience largely remains unchanged, and Vista-phobic users will probably appreciate that. That doesn't mean SP3 is without merit, though; its improvements are useful. Besides scores of security improvements, bug fixes, and other stuff that's already been released through Windows Update in the past two and a half years or so, it also includes.

Full story: extremetech.com