If you google "squirrel proof feeder reviews" and click the top entry you'll see a couple of squirrel proof feeders.

They're not cheap. I made my own using an old upturned large plastic tub with the peanut feeder suspended below. It works well.

Here's a link to a photo of my home made version.

http://www.flickr.com/photos/31559373@N00/5833278401/in/photostream

If I knew the answer to that I'd be a millionare!!! :)

you could buy peanuts for the squirrels and make them a plus in your garden and get a gaurd for your bird feeder .