I am in the market for a road bike and I have gotten a couple of different opinions on stad over height. I have been told 1 inch clearance minimum and have heard that it is not that big a deal. I have also been told the right size for me is anywhere from a 47 to a 52. I could probably fit on anything in that size range, should I then use stand over as a determining factor on what size I end up with??? Thanks for helping out a road newbie!!

Don't use stand-over height. Since you are in Manassas there are lots of good shops to go in, talk with knowledgeable employees, get sized, and talk about what's best for you. Bike Lane in Reston or Springfield, Spokes in Vienna or Fairfax, or Freshbike's in Arlington (which has mostly high end bikes but one of the best stores anywhere) come to mind.

You want to be able to straddle the top tube and not rack yourself when you lift the front of the bike to go over an obstacle such as a curb, but other than that, stand over is unimportant. You really need to be concerned with the top tube length fit wise. I agree with StanSven, get to a bike shop and ride some bikes.