alpha question

so I take a plane, uv map a texture to it, and I want the black parts transparent.

So far, the way Im doing this is, create a material, load the same image, set it to z-transparency and to affect only the alpha. then selecting map to, and mapping it to UV- and writing UVTex which is the default name of the first UV image that I mapped to the plane? rite?
Im just not sure if thats the correct way to do it.