You'll have to determine the new equivalents to the mso* objects - hopefully this is documented somewhere on MSDN in fact, this page on Migration From Office 97 to Office 2003 looks promising. If not, you'll have to go through the VBA object inspector in Word 2003 and try to figure it out.

I also seem to remember somewhere that Word 2003's native format was (or could be) XML-based, so you could just ignore automating Word altogether and create files in the format it's expecting. Especially so as the link you reference just seems to be creating a Word document, and isn't doing anything "interactive" with Word. Mind you, if the Word xml document format is anything like I suspect it might be, then that way could lead to madness ;-)

Hope that helps.