If you in general want to skip a whole drive, this is not so easy. The problem is that you skip top down. Consequently, NW will not even proceed to the subdirectories.
For an easy solution, the best method would be
- move all unwanted files in a subdirectory
- Setup a directive like this:
<< "E:\unwanted" >>
+skip: *
<< "E:\wanted_1" >>
+always: *
<< "E:\wanted_2" >>
+always: *
Also be aware that you must quotes on Windows directories.