Why do the games are not coming in widescreen in windows 7?

i'm using toshiba 14" laptop. initially i used windows vista. in vista all my games r working in widescreen. recently i upgraded to windows 7 . in 7 all my games are seen only in the centre of the screen ... there is black empty spaces on the both sides of the screen.... what should i do for the widescreen appearance of my games in windows 7... somebody please help