Aw, and here I thought this was a recent debate. :(
Anyway (if anyone still cares about all this)... Nosferatu, a Symphony of Horror is indeed an adaptation of Dracula. However, it wasn't that the Stoker family got pissed and so the filmmakers had to change the names of the characters; it was an unlicensed adaptation (they hadn't gotten the rights), so they simply changed some of the names and story pieces to try and get around copyright protection. Count Orlok is indeed supposed to be Dracula.
After the film was released, it was then that Stoker's widowed wife threw a fit and had all prints of the film burned. Thankfully, some survived and we're able to view the film today. There was a pretty big restoration handled by Kino International a few years back that restored more of the film, and is to my knowledge the longest version of the film currently available.
There is a 1979 remake by Werner Herzog titled Nosferatu: Phantom der Nacht (a.k.a. Nosferatu the Vampyre) which uses the names from Dracula instead of the ones in the original Nosferatu, but is again essentially a remake of that film and not a more proper adaptation of the novel.