To change the Startup of a Service or Driver, edit:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services

Navigate to the Service or Driver and select it. In the right hand pane, double-click the Start value and change this REG_DWORD to:

 Value   D e s c r i p t i o n 
 0   Boot: Loaded by kernel loader. Components of the driver stack for the boot (startup) volume must be loaded by the kernel loader. 
 1   System: Loaded by I/O subsystem. Specifies that the driver is loaded at kernel initialization. 
 2   Automatic: Loaded by Service Control Manager. Specifies that the service is loaded or started automatically. 
 3   Manual:. The service does not start until the user starts it manually, such as by using Services or Devices in Control Panel. 
 4   Disabled: Specifies that the service should not be started.