I agree, tablets have been the ultimate fixation in computing devices for a long time. We need only look at scifi -- how many shows have people carrying around pencil-thin panels and pulling up a ship's specifications while they walk and talk with the warp engineer, pounding on a glass table to engage weapons system, or other things like that? Apple hit the right combination of price and style at the right time, and imo took the scifi conception much more literally than their competitors, to bring tablets mainstream.
It's all about the multitouch. Sure a windows tablet with multitouch running XP would have been massively inferior to the iPad but it would have started to realise the potential of the form. Instead years of Wacom pen tablets just made people hate the idea.
