TacoX, do you have the anti-glare coating on your glasses?
Since I got it on my glasses I never get headaches and rarely get sore/bloodshot eyes from working at PC.
Staring at the monitor too long will stress your eyes, but it won't ruin your vision.
Eyesight is all genetic, and it worsens as you get older.
I know some people who have 20/20 and they play WoW 4 hours a day for years, and i know some people who are legally blind and they barely look at an electronic screen.
the reason those of you talking about being on a laptop is easier then a monitor desktop is because most laptops have a light sensor and adjust the brightness of the laptop screen.. similar to auto headlights on cars when it gets dark outside.
Almost all modern laptops have this, including Macbooks, HPs, Dells, etc