Well, its 24 x 80 if its a 80GB drive.. That would be a loss of about 2GB.
But, in your case your only really losing 24MB, which isn't too bad..
Its basically just easier for the average person to think about a gigabyte being 1000MB, and thats what most people really think it is. I don't hear much people saying that its 1024MB, because most people unfortunately don't know nor care.
Like in the example with me calling my host.. they honestly had no idea it was 1024. What can we do? Its 24MB in this case, so arguing it really gets us nothing but frustration.
All the same, enjoy the drive.. ;-p