Canes, the best place for that 500 in your room may well be 1/3 or 2/3 of the way down your side-wall relative to the front left corner. It may sound best if it's moved a foot or so away from the wall.

The easiest way to locate the correct position is to place the sub where your main listening position is. Play a tune with bass. Then crawl along your side-wall and locate the positions where the smoothest bass is happening. Put the sub in any of those positions.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated