Depends on your commute. If you are sure you'll be on smooth roads the whole time, might go with the skinny road tires for better speed/efficiency. If, like me, you have to go through a bunch of gravel and poorly paved roads, you might want to stay with the mountain bike tires.

The main thing I would do is put a rack on the back. Very few things I hate more than a long commute while carrying a heavy backpack full of my laptop, change of clothes, and various bike tools (and any groceries I had to get along the way). Dragging a 15-20 pound pack on your back for a 30 mile round trip commute can be brutal.