Error message "Microsoft Bus Driver should be loaded in your system while installing Realtek HD Audio Driver" shows during RealTek High Definition audio driver installation under Windows XP.
LastUpdate : Mon, 27 Jun 2016
Answer
To resolve this issue, please install Microsoft hotfix KB888111 or update OS to Windos XP SP3.
Microsoft hotfix KB888111 download link: http://support.microsoft.com/kb/888111/en-us)