Manage Windows Update From Remote Server

I have over 100 computers i am resposible for and they are spead out across the country. However there is no main server that controls all these clients. they are jsut out there like a bunch in individual home PCs. is there a way using SUS or whatever that I can force windows updates to them in one large batch file each month or quarter? Currently logging into each computer and telling it to update is more than time consuming. Please some one point me in the right direction.