How do I get a model from one file to another?
How do I load existing materials?
I am using Blender 2.5 on a Macintosh.
Shift+F1 to append things from one blend into another. Append a material and then you can select it from the dropdown list of materials.
http://wiki.blender.org/index.php/Doc:2.5/Manual/Data_System/Linked_Libraries