theravadamonk:
I was going to suggest using a transparent background and draw a pie chart with different sizes for each donut, then stacking the images together. While reviewing the thread, I noticed that marto posted a link to an IBM developerworks article that shows how to customize pie charts. I think stacking transparent pie charts with the customization bits (such as hollowing out the pie chart and annotating it) in the IBM article should be able to get you where you want to go.
...roboticus
When your only tool is a hammer, all problems look like your thumb.