This shot may not have had much time in which to be taken, but you did a very good job with it. The focus is what makes this shot work, and b/w was a very good choice to catch the mood and somberness of such a place. :)
Black and White was the perfect choice for this photo. I would like to have seen what you would have done if you'd had more time to capture the shot. =}
I too like the B&W. I think all American's should visit Arlington National Cemetery to realize the price our country has paid for the freedom many take for granted.