If you're driving in Vienna proper and the speed limit is 25 miles an hour, do not exceed 25 miles an hour. Their speed limits (particularly on 123) are ludicrously low, and the police take full advantage of it.
VA police are notorious sticklers for things such as changing lanes without signaling (which, in some contexts, I believe can be deemed 'reckless driving'), and are generally very difficult.
In their defense, however, drawing from comments above, people here are ALWAYS more important than you, and it's YOUR fault for being in their way. I'm sure I'd be a little bitter if I had to deal with these people day in and day out.