Nowadays you don't see too many crackers using Backorfice anymore. However, there are plenty of variations on it that are really popular. I've used one called SubSeven before, and it DOES allow you to view the victim's screen. It's got a really neat GUI that allows you to use your mouse on the copy of their screen (which you can set the refresh time for) just as if it were your own screen (i.e. close programs, go back and forth through web pages, etc). Of course, there are many other prank and destructive tools that come with SubSeven as well.