Rob has a process in his Mac called "User Event Agent" and he doesn't know what that is. Is it necessary? Leo says it is. It just monitors all of his activity. This includes mouse key presses, typing, etc. If he were to stop it, his computer would become unresponsive. He shouldn't really get caught up with what he finds in the Task Manager, especially when the processor and RAM are being used.
Leo says that something is taking up a great deal of RAM and it's causing the computer to labor hard and slow down. "Services" are just things running in the background. He can examine what services are running to get an idea of what's slowing down his computer by right clicking on "My Computer", then click "Manage", and click the "Services" tab. This will show him a list of all the services that are running. Windows may also be indexing the computer at bad times.