I found this at wikipedia:
realsched.exe (RealNetworks Scheduler, also found as Evntsvc.exe or TkBellExe) is a background process, bundled with the installation of RealPlayer. It is intended to provide users with information about critical RealPlayer updates, and as such is only functional when a computer is connected to the Internet. It is non-essential to Windows and to RealPlayer. The process generally takes 136k of system memory. Realsched.exe has been known to exhibit excessive CPU usage. The file can be disabled with Windows software tools and moderate computer skills.
As there are many service host (svchost.exe) processes running you have to try and identify the calling program. Usually when you bring up Task Manager there will be another program where the figures under the CPU column will be greater than zero. The most common program is wuauclt.exe (windows update client) so if that is not listed it will at least narrow down your list of culprits.
downside
