It's an absolute must to calibrate your monitor if your doing any kind of color critical work. Here are a couple useful links that show how to calibration your monitor using some of the different devices available:

Spyder3: [link]
Eye-One: [link]
Pantone ColorMunki: [link]
Pantone Huey: [link]

All of these devices calibrate your monitor's brightness, contrast and saturation settings for different viewing environments. They range in price based on their features. Even if you use the cheapest device, it's still better than working on an uncalibrated monitor or one that has been calibrated by eye.

Color management scares people off because it's still a complicated subject. Thankfully, I was forced to learn it when I worked at Entertainment Weekly and it's been a huge part of my professional work since. I highly recommend you learn as much about color management as possible. In the long run, it will make your life much, much easier!