In my opinion, whey protein is more useful if you want to 'bulk up'. I know a few very fit and healthy people, from an Ironman (who used to be a professional athlete), to a vet60+ elite fell runner. A pub discussion a while back, whey protein came up in the chat, and both of them explained that they MIGHT use it if on a really heavy training schedule. For them, 'heavy' meant 4-5 hrs a day, 6 days a week of training.

A general reasonable healthy diet is going to do you far more good. To me, a healthy diet means avoiding lots of processed foods, and cooking from raw ingredients when possible. We make plenty of stirfrys, chilli, pasta meals, and in wintertime lots of casseroles and stews, and most of those are from base ingrediants.

Must admit, I do sometimes quaff protein shakes after going to the gym, but I've never really done it scientifically enough to know if it makes a difference. The one thing I'd say is they can come in hugely varying qualities and ingredients - so check the label! Particularly from a kcal point of view - they can immediately negate a 4 mile run in one glug.

As the other chaps have said - a clean diet is the main thing. If you eat natural food you won't go far wrong.