Maybe it works to set the SystemResponsiveness value to 20 (decimal) in registry entry HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionMultimediaSystemProfile. (Open the registry editor by clicking Start -> Run -> regedit) If SystemResponsiveness is set to 100 (default in Server 2008), it means that all processes are given a higher priority than multimedia. In Windows Vista the default value is 20.
Source: http://nerdfortress.com/?p=12
