Send Commands to Multiple pc's?

I need some recommendations on this.

I'm looking for a program that can be used to send commands out to multiple Windows PC's on the network, either by talking with AD for the list and selecting the one i want, or interogating a list file.

All ireally want it to be able to accept is command line instructions, which can use to run network based batch files or something as simple as "gpupdate".

any help would be greatly appreciated.

Cheers

James D