Today I was watching a video from Channel9 and there I have found that the way windows service works has been changed in windows 7. The common scenario is to run common windows services on startup. Normally this takes long booting time and shutdown time. Also the services startup automatically do not need all the time. For example "Tablet PC Input Service", this service starts automatically when computer starts but this is not needed if you don't use tablet PC. So this type of services do nothing but take up computer processing power and memory and causes slow start up and shut down.
To get rid of this problem Microsoft Kernel team is devised a new way of starting and stopping services. This is trigger based. So now in Windows 7 all the services will not start automatically rather starts by kernel when some kinds of trigger fires. For example the "Table PC Input Service" will not start on startup. But some kind of tablet PC will be attached then the kernel will identify that for this the "Tablet PC Input Service" needs to be started, and start the service. And the tablet PC will be unplugged the service will be stopped by the service.
So this is great idea! Microsoft was started Vista a brand new way and now in their next OS windows 7, they are looking how to improve performance for Vista-next OS.