UV Unwrap window

I’m pretty new to blender (using 2.48a still), have been familiarising myself with it in order to export game models. The one problem I’m having at the moment is that I seem to be able to load bitmaps into the uv unwrap window and assign them to my model using the different unwrap commands (u + whatever), except that those textures are not in my materials list (ie. not in the texture list in the shading panel / textures).

How is this possible?

It also seems to be messing up my DTS exporter, though I’m sure that’s not the only problem with it.