You should consider your actual setup. Even a 23" monitor is pretty big, and you have to sit far enough away from it so that you can take in the whole screen at once. That'll also make sure you don't see the individual pixels (regardless of how good a monitor is, if you're close enough, it will look bad).
You can use a calculator like this, though it's designed for home theater setups, but will give you a sense of what you'd want for using the monitor for watching movies, and for some gaming (might want to be closer for online FPS):http://myhometheater.homestead.com/viewingdistancecalculator.html
The SMPTE recommended distance gives you a decent approximation because it's a 30 degree viewing angle, which means about 2/3 of what you see is within a pretty good part of your vision.
The fovea (center region of eye, highest density of photoreceptors) covers only a few degrees. If the monitor is too close, you have to constantly move your eyes to see what's going on. http://en.wikipedia.org/wiki/Fovea_centralis