How do I configure my monitor/operating system for optimal color display?

I'm a web developer, and for a hobby I take photos and edit them on my computer. I've found that sometimes I miss stuff on my own monitor that are apparent on other monitors (aliased edges that didn't appear on my screen, for example.)

What tools/methods can I use to get the optimal settings for my computer?

Also, is it common for VGA (DE-15) cables to show less color detail than a DVI cable? I recently got a new monitor at work and it turned out that I couldn't see the difference between white and any color with RGB values above 230 or so until I switched to a DVI cable.

I find the Lagom LCD monitor test pages to be very useful for this. It's the first site I visit after hooking up a new monitor.

I've also noticed the same difference in VGA vs. DVI, but I only have personal observation to back that up, no actual data. Perhaps somebody more knowledgeable about the tech could give us a definitive answer.

I got myself an Spyder2 Express for $120 (shipped to another country, so it must be much less on the States), and it has been a life changing experience.

Before calibrating my monitor, I was uncertain whether my pictures (I am also a photographer) will be printed or shared just as I see them. After having shared some, and people told me that they were too dark and color-casted to yellow, I got fed up and bought the Spyder2Express.

The process is really simple, just stick the device to the screen, run the calibration software, and it automagically creates a color profile according to the colors measured.

After that, I loaded up some pictures on a white background, and boy it was white. No cast whatsoever.

After having suffered for not having the correct color calibration on the monitor, I will never go editing again, without making sure you have the best possible settings on a monitor. NVIDIA tweaking or Adobe Gamma can go so far, but it is not an exact science and depends very much on the eye of the calibrator. Using a device will rule you out of the equation and can be much more accurate what you get.