Most designers should already know this because they need correct color, but even for every day use from games and DVDs to browsing the net, it's a good idea to calibrate your display because everything will look much nicer. Here's a detailed tutorial on how to tweak your display for both OS X and XP.
This tutorial will not only show you various Photoshop techniques for converting color images into black and white images, but also explain the advantages and disadvantages for each technique.
