2 megapixel cameras has very good resolution - Full HD. For most of places this is enough to see everything that you need. Full HD resolution it is correct format for modern monitors and TV sets with HDMI inputs, they have 16x9 resolution format and cameras with 2 megapixel has 16x9 format too, that means that image of camera will be without frames boarders image will take all space of you monitor.
In our practice 2 megapixel cameras is optimal standard for price and quality. So, if you want to have good quality system for not so big money - this system is for you. For 2 megapixel HDCVI cameras you can use 5, 7, 8 series HDCVR.