When using a .NET client to communicate via HTTP, you may notice an HTTP header that looks like this:
Expect: 100-continue

Depending on how stringent the web server is, it may or may not be fine to have this extra header. If you must remove this header, it's very easy to do in .NET 2.0. Just include the following line of code in your application:

ServicePointManager.Expect100Continue = false;