and for the other question about installing fce on an external drive. You must install final cut on your internal drive. You can capture and edit from an external drive. I believe i said this in an earlier post in this thread.
It doesn't matter, I've said it twice in this thread. The Graphics Card has no impact on performance whatsoever when editing in final cut. This decision should be made on what other stuff you'll be doing. Will you be doing gaming or using other applications that require 3D rendering?