Diagrams in MS Office editable form

For any graphics I use in my deliverable documents, I am required to produce a file with the graphic in a format editable by MS Office products (i.e. PowerPoint). I assume right now my only option is to export a diagram as XML, then use an XML to PowerPoint converter. Are there any suggestions as to the best way to do this? For example, would traditional or simple XML be better? Are there any converters that work better for this case than others?