File server hardware

We are about to put up a windows 2003 server in our kontor fælleskab. Primarily its purpose is for file sharing and storage, but the same computer will also run a dev version of flash communication server (for streaming realtime video but only a few streams at a time since its the dev version). Can anyone tell me (in danish) what kind of hardware is the most important. That is RAM, processor speed, router capabilities... What will make it most problem free and what can I do to make it escpecially effective?