Fellow DARTer Chris B. just informed me of a new marathon (and half marathon) taking place on April 24, 2010 in Roanoke, VA called the "Blue Ridge Marathon on the Parkway". I realize that this isn't exactly a race that's local to the Davidson area, but it's less than a half-day's drive.
The marathon was created to celebrate the 75th anniversary of the Blue Ridge Parkway, which connects Shenandoah National Park in VA with the Great Smoky Mountains National Park in NC.
The race begins and ends in downtown Roanoke and appears to be quite challenging as well as scenic. Scenic in that most of it takes place on the parkway proper; challenging in that there will be a lot of hill climbing, especially in the first 15 miles.
I'm mentioning this marathon and half right now as I'd imagine that it will fill up quickly. So if you're interested you should register quickly. Here's the official link: http://blueridgeparkwaymarathon.com/
The Roanoke Times profiled the new race, and you can read about it here: http://www.roanoke.com/news/roanoke/wb/216317