There is a difference between a startup folder and the location for
normal.dot. It sounds as if, for Word 2003, you have normal.dot in the
startup folder. You do not want this. If it is normal.dot you are talking
about, you should simply point the user templates folder to the same
location for both versions of Word. Note, I am not advising using the same
normal.dot for two versions of Word on the same computer. I don't know
whether or not this would cause problems. I keep my customizations in
separate global templates, which I do share across Word versions.

See http://addbalance.com/word/movetotemplate.htm for step-by-step
instructions on moving / sharing / copying / backing-up customizations
including AutoText, AutoCorrect, keyboard assignments, toolbars, macros,
etc.