My laptop is a 15.4" 1400bySomething resolution, so the pixel-per-inch count on it must be higher than with the 21". It's fine for my needs, I guess. the 21" should do just fine
I am using 1600x1200 on a 15 screen, all is VEY SMALL, but I see so much I can not give it up and my head is 5 inches from the laptop
I will count the tracks and slots and post it
If you can work with 1600x1200 on a 21", it is perfect.