How much does pixel pitch of monitor matter when editing video/photos?

"For a 1920x1200 24'' monitor, a dot pitch of 0.27mm is indeed expected. This give you roughly 94 pixels per inch. Picture is sharp and true (assuming you use the monitor correctly, of course. Meaning using the native resolution and correct refresh rate).

How do you know?

Use this calculator:
Display Calculator.
Input the data from your monitor
size and native resolution.

The result will give you the most appropriate dot pitch. Variations happen among vendors. Anything within 0.05 mm range is acceptable and imperceptible even to the most trained eye."

"Pixel pitch does not matter much, but the higher the pitch, the better the contrast, brightness and viewing angles.
But if you want to do photo and movie editing, panel type is much more important. I think in your case an IPS panel is best. Those panels have true 24 bit colour reproduction (TN panels use flickering/dithering techniques to achieve 24-bit like colour), acurate colour, great viewing angles, good contrast, yet are pretty fast in response. Have a look at the DELL U2410 or the HP LP2475W for example."