Here we see the county by county results for Virginia's Democratic primary. Obama counties are in green, Clinton in red. To get a better sense of the magnitude of Obama's victory, though, this map (courtesy of Larry Sabato) is perhaps more useful, scaled by population.
Fairfax county is the epicenter of northern Virginia's growth over the past few decades and the driver of Virginia's increasing tilt towards the Democrats. It is also here that Obama gathered the largest part of his statewide total.