You can also go on you tube and watch videos on how to remove tires. like this video: http://www.youtube.com/watch?v=-yMs3g2q0cw and many more. It also helps to use a tube one size smaller then the tire if possible.

But don't use a screw driver. The nicer tire irons like the Park plastic ones or Pedros which may be better then the Park, or the Soma Steel core levers, or the QuikStik. I use the Soma levers and to get the tire started then rip the tire off with the QuikStik.