We claim, the ornamental design for a notebook computer, as shown and described.
FIG. 1 is the front perspective view of a notebook computer showing our new design;
FIG. 2 is the front view thereof;
FIG. 3 is the rear view thereof;
FIG. 4 is the left-side view thereof;
FIG. 5 is the right-side view thereof;
FIG. 6 is the top-side plan view thereof; and,
FIG. 7 is the bottom-side plan view thereof.
The dot dash lines in the figures represent an unclaimed boundary line and form no part of the claimed design. The broken lines illustrating portions of the notebook computer are for environmental purposes only and form no part of the claimed design.