Simple program to convert files to .dwg made in c#

I need a application to convert; - .pdt to .dwg - .dwf to .dwg - .dwt to .dwg It must support all AutoCad versions It must be possible convert multiple files at same time. It must be done in Visual Studio 2010 using the c# language. It should have the option to run on local pc or on a server. Note that after conversion the .dwg must maintain all the objects as polilynes, arcs, etc and the layers, line types, colors,etc as the original one.