You might think about searching this site as there are several threads on this subject.
Here's a link from Harvard that might save you a little time:
http://www.hsph.harvard.edu/nutritio...e/protein.html
I also agree with Stompy's ON comment - Optimum Nutrition powdered protein. Ice cream flavor is great and you can change it easily. Plus, add the Carnation malt powder for added flavor, texture and carbs.