I tried the skins in FCKeditor and made a new one, which looks more like Word 2003. The contextmenu now looks like the original office contextmenu. I also used some of the buttons of your office 2003 skin.
If you want to see it, have a look.
Actually it's all about the .css files and two different images ("images/bcg.png" and "images/bcg_context.png").
I tested the changed skin in IE6 and FF1.0: it works!