I recently upgraded to a new computer and re-installed CS6 (now 64bit), when editing my images after resizing to approx. 1024x768 for posting on the web the image barely fills 2/3 of the working space, however when viewing it on the forums after posting it fills the screen.
I can get it to nearly the same size by changing the view to "fit on screen" in CS6 which the shows the size as +/- 120%.
I've set the display on the computer to the optimal (recommended by windows8) and the size of images and text when browsing is 100%.
Is there a way to change the resolution or whatever in CS6 so that it matches the size when viewing on the web as it poses a bit of a problem doing PP on a image smaller than what it is really shown as one is never 100% of the sharpening etc and I do find that it can happen that the image is under- or over processed.