In Office 2000 there is no Picture property to popup menu controls (but it would be nice!). If that works in Office XP, I'm not sure why a reference to the MSO library doesn't work, but in my experience references in VBA don't "carry back". Probably MS doesn't allow it so everyone has to buy their new product, but I don't know much about how VBA transfers versions of MSO library references.

The best you get in Office 2000 is the PasteFace function to paste an image from the clipboard. For anything other than standard images, you have to send the image you want to the clipboard and then PasteFace to the popup control.

Hope that helps, at least a little.