First thing is if you have not done it yet is to assign a global coordinate system in your drawing. Once you have done that open google earth and view the location you want. In the file pull down menu go to import then the next pop up will give you a list where you can select google earth image. and it will import the image at both 1:1 scale and in its proper GIS coordinates.  I use this method in Civil 3D 2008.  I hope this helps.