Windows Management Instrumentation Service - WMISVC.DLL
Wmisvc.dll is a service provided by Microsoft. It provides a common interface and object model to access management information about operating system, devices, applications and services. If this service is stopped, most Windows-based software will not function properly. If this service is disabled, any services that explicitly depend on it will fail to start.
By default, this service runs as "automatic". You'll want to leave it as is. Disabling it can cause numerous problems.
A description of services that run under svchost in Windows XP can be found at http://support.microsoft.com/default.aspx?scid=kb;en-us;314056.
A description of default services running under Winodws can be found at http://support.microsoft.com/default.aspx?scid=kb;en-us;Q250320.
Service
Microsoft