Instead of using task manager to stop/start services, type “services.msc” in the Run box. From here you can see/change the startup type - if disabled then the service will not be able to be started.
For more information about how to tweak services in Vista please read
http://www.blackviper.com/service-configurations/black-vipers-windows-vista-service-pack-2-service-configurations/
There you can find multiple configs - default, safe, tweaked and bare-bones.
Most likely after trying these for a while, you will settle on default or safe or something in between.
All services are linked to pages describing their function in some detail.
Beware that usually, there is little to gain by disabling services and quite often there can be much to lose.
