How many different combinations of the position of two black squares in a 3x3 square grid of remaining white squares are possible if you consider any combination that can be rotated to become another combination the same?

To illustrate:

http://i204.photobucket.com/albums/b...mbinations.png

The top set of combinations would be considered the same because the left one, if rotated 90 degrees clockwise, becomes the right. The bottom set of combinations would be considered different because they cannot be rotated in any way to become one another.