Well don't they usually say in the movies something like, "The Soul weighs more then a banana" or something along those lines?
But defineatly believe in ghosts. I don't know if they can go through walls or anything, but poltergeists (you know, "there heeerrrreeee"?) scare me like hell!!! After watching the television show "A Haunting" on deiscovery channel (it gives so much detail and everything) it all looks so real... and scary...