Ok, just tried it out.
Do this, after you create a word file on your Axim, press Menu-->Save As
There four formats:
*.docx
*.dotx
*.rtf
*.txt
Please save it as *.rtf or *.txt. Then your Word 2003 can read it.
If you want to save it as a .docx, you have to download the compatibility pack for Word 2007. Here is the link:
here.
Lastly, another method is just to buy Office 2007.
Or one picture is worth one-thousand words: