My sisters computer has a Quantum 20.4 GB HD in it and she called tech support and they told her the hard drive it was shipped with was a Quantum 20.56 HD. Is it the same HD or not? My reason for asking is that I am now being accused of stealing her HD and switching it and. My HD also reads one number and tech support tells me a slightly different number. I know its the same HD but how can I explain it to her that its the same.