The ornamental design for a notebookcomputer, as shown and described.
FIG. 1 is a perspective view of a notebook computer showing my new design;
FIG. 2 is a front view thereof; and,
FIG. 3 is an enlarged view of an indicated portion of FIG. 1.
The broken line shown surrounding the shade lines of the claimed surface represent the bounds of the claimed design, while all other lines are directed to environment and form no part of the claimed design.