Can someone recommend me a desktop rig that will be use for teaching in my classroom?

The parts that will be reuse are :

1. Samsung 850 EVO 250GB
2. Dell U2312HM
3. Leadtek GTX970

and at the same time, please do recommend me a good projector that can be project to the wall in a small room.

Budget would be quite flexible but want to maximise the cost to quality ratio. Best bang for bucks spend.

As long as smooth interface, reliable and can get the job done.

Thanks..