Simple Web Browser with changable user-agents

A simple web browser that will navigate to a typed in website address but the browser needs to have all the headers a normal browser would have such as firefox and internet explorer. BUT the unique part is to have a drop down box on the program to select which headers to use, whether its firefox or internet explorer. The headers and user-agent etc need to be exactly the same as the original browsers and to be able to handle the content size and cookie just like normal. When a webpage is opened the requests need to use the chosen headers throughout the loading of the webpage and also carry on using the custom headers until another browser is chosen in the drop down / selection box. I need this written in vb6 or vb.net and i need the source code