 A few services not essential for server environments are disabled by default for stability reasons, most noticeable are the "Windows Audio" and "Themes" services; users have to enable them manually to get sound or the "Luna" look as per Windows XP.The hardware acceleration for display is also turned off by default, users have to turn the acceleration level up themselves if they trust the display card driver.In December 2005, Microsoft released Windows Server 2003 R2, which is actually Windows Server 2003 with SP1 (Service Pack 1), together with an add-on package.