Welcome to the land of video surveillance lunatics. Be sure to check the WiKI, in the blue bar at the top of the page. Study, carefully on a real computer, the Cliff Notes in there. There is also a lot of other good information for sizing a system and keeping it safe on the internet, foil the "phone home" features. Read, study plan, ask questions, revise plans and test before spending money. It'll save you time, frustration and money in the end. There's tons of reviews here on cameras, and NVRs to help confuse you even more when trying to make a decision.