There seems to be a big province-wide push toward the use of interactive whiteboards, such as SMARTboards. I think that these are good devices, and I am particularly impressed with the rear-projection units. They are very intuitive to use, just like drawing on a whiteboard, and they also fulfill all of the functions of a regular data projection screen.
That being said, though, for the high school level I am more in favor of tablets or, if you prefer and can afford them, touch screens. Tablets, such as the Wacom Bamboo, are nice because they are inexpensive ($80 and up), portable, durable, pressure-sensitive, and have a quick response to drawing motions. Touch screens have some of these features, but are certainly not inexpensive.
In my classroom, I use a tablet for drawing on PowerPoint presentations, among other things. I also use the free program ZoomIt. At some point I may get a wireless tablet, but for now I'm just using a long USB cable. I like the flexibility of being able to click through the prepared show, but also add or embellish as we go along. And my penmanship is improving.