I am using visual studio 2010 and I am having a .DWG file which I want to open in autocad. Till now I have used this.
Process p = new Process();
ProcessStart
Take the Autocad .NET libraries from Autodesk Sites (http://usa.autodesk.com/adsk/servlet/index?id=773204&siteID=123112)
Then you will be able to use Application
and Document
classes.
They will give you full control over opening and closing documents within the application.
You can find many articles on that, and can ask further questions.