Yes, without a doubt the display IS the most important component in your system. Without it, your computer is useless. If you use your computer for hours and hours on day, it is the only component you're looking at!
You only have one pair of eyes! Treat them right! There is nothing wrong with spending a few more $$$ on the monitor and buying a video card that is a generation or two behind. A good monitor will outlast any other component in your system. A $700 video card will be long obsolete before the monitor will. Just be sure to invest in a good UPS to protect it from surges and power anomalies. Set your screen saver to power off the CRT after an hour of non use. This will ensure that the CRT heaters last long. Never turn the brightness any higher than necessary.
Cheers!