GET or POST?

Hi There;

I'm trying to access GeoPlanet using WCF in .Net 3.5.

When I use a GET method I get the error: The remote server returned an error: (406) Not Acceptable.

When I use a POST method I get: The remote server returned an error: (405) Method Not Allowed.

Obviously I'm doing something wrong but it would help to know whether I should be using GET or POST in the first place.

Any suggestions about possible causes of the error would also be greatly appreciated.

Thanks in Advance.