But the original question seems to be still left unanswered. I have grappled with this one myself.
Basically, it is finding out the percent zoom I should use so I could view a bitmap in a vector program at the real size it would be displayed on screen (on a bitmap program at 100% zoom or in a web page). There seems to be no direct way of doing this in a vector program. Being resolution independent, it is not easy to get a preview of a picture in it's actual pixel size in relation to the monitor, it seems. I could be wrong, though...
Take Behzad's screenshot, for example. One is 72 dpi, the other is 96. Different resolution but same size when printed, so a vector app displays them the same size. But both pictures when opened in a bitmap app and displayed at 100% zoom would be differently sized...