Adobe Photoshop for Raster
Adobe Illustrator for Vector
Painttool Sai is really good for drawing/sketching/otherwise real artwork
If he's interested in doing 3d, get zbrush. For tutorials on 3d, Digital Tutors is the best place to start.
A tablet is great as well. Works for drawing and 3d. Entry level ones start at around $75 (Wacom Bamboo). The mid-range is the Wacom Intuos3 or Wacom Intuos4 ($300-$700). High range is Wacom Cintiq ($800-$1400) which is due to on-tablet screen, extreme sensitivities and size.