All you have to do is download the theme by clicking on the "Download the
Windows Mobile Blue" (for example) link on the page. Transfer the .tsk file to the Windows folder on your PPC with ActiveSync, and it will be available in your themes list (Start > Settings > Today).
Unless you were just talking about the colors rather than the actual themes. Then you will have to wait for a theme editor if one isn't available for WM2003. Then you can use those colors to create your own themes.
Actually, shouldn't any old theme editor work for WM2003, like the one from Microsoft? The .tsk files should be the same. Of course, I won't have my 2003 device until tonight ( :clap: ), so I can't tell.