>If you took the card out of a different camera or have >changed folder names, for instance, you would still have those >pics even after formatting. Deleting the old folders under >whatever computer OS you have usually will do the trick.
I don't think this is true. When you format the card it should erase everything no matter what folder it was in or if it was used in another camera.
But as noted when you use the menu you have to make sure you go through all of the steps. I always do it that way instead of the two button method.