2D object resolution

I'm new to Unity and am tinkering with the graphics. I'm trying to make 2D objects by putting textures on planes and aiming the camera (in orthographic mode, of course) at their faces, but I can't seem to get the resolution of the objects quite right. I want each pixel in the texture to take up exactly one pixel on screen when the game is playing.

How do I set things to force this to happen?

As Jaap mentions SpriteManager is a good package and in particular SpriteManager2 has a Pixel Perfect option - http://www.anbsoft.com/middleware/sm2/

It's difficult to get it exactly right, part because OpenGL handles the way texture pixels are mapped to screen pixels a bit different. Possibly a good point to start is: