combining an image with 3d graphics

I would like to know if there is a way of overlaying a 3d scene with an image (such as a bitmap) or vice versa.
If the only way to do this is by creating a transparent textured surface (with the texture being the bitmap) right up close to the “camera” what is the best way to go about this?
Thanks very much,
Sam Howman.

Ooh yeah - an advanced question - not.

Look up glOrtho()