My workaround solution to get Numbers charts into Word 2004 and 2008 is to place the subject chart(s) onto one or more sheets - I tend to put each chart on a separate sheet - then export the charts as PDF files, set for "Best Quality" and to the "Current Sheet". I then generally drag each individual PDF into Word and adjust as necessary for scale and position.
I'll admit that IMO Word 2004's graphics engine really wasn't (Isn't?) consistent or that great at handling non-native graphics, and I've encountered the black picture syndrome dozens of times, and just try reimporting until I get what I want. I've also used Apple's Preview application (via Automator) to generate TIFF and JPG files of the PDFs I generate, and almost all of the time one of the resulting files gets me what I need.
One last method of shoehorning an image into either Word application that's worked wonders for me since Word 2001 is to choose the graphics element you want to get into Word and copy-paste it into Word, letting the Clipboard handle the translation; I've used this technique just this morning to get two graphs (a copied one-page PDF from Preview and a small chart from Numbers) into Word as graphics, albeit into Word 2008 - the finished product was exactly as I'd expected.
One last option is to copy your elements, one at a time, to the Clipboard, and to use the Word "Paste Special" command, choosing the "as Picture" option; the pasted elements likely will look a little fuzzy, but they're in your document.
Good luck - I hope my offering helps, and if a more direct method were available, I'd love to know what the better solution is!