VT20 has no issues if content is being watched with side window-curtains fully opened, even in the noon. cant say though for opposite facing windows, as i have none, but other members here would be able to throw light on that. for that matter, take just today's case. was playing bad company 2 today in the evening, around 1700 hrs. windows were fully covered. i felt somewhat uneasy, as always, to sit with such 'closed-room' conditions, esp. in the evening, and threw open the curtains as well as the window to let the cool evening breeze come in, and what a pleasant change it was, with NO NEGATIVE EFFECT whatsoever on the brightness output of the TV, considering games where lighting/brightness is an important thing so as not to crush details.