@Ray7:I have stated multiple times that WP7 route would be a mistake. Once good Win8 tablets start shipping I bet iPad and Android will quickly lose attractiveness. iPad and Android tablets do not ship with desktop OS, which means customers have to have another machine. Having two computers does not make an economical sense to a large class of customers, who will go with Windows 8 because with Microsoft they could combine the role of iPads (mostly media consumption devices) with the role of laptop or desktop computers into a single hardware product. Connect keyboard and mouse, you've just transformed your tablet into a laptop. Connect external display, you've just created a desktop machine. You can't do that with iPad.
If they limited themselves to WP7 and media consumption role for tablets then they couldn't differentiate themselves successfully from the competition, somethin WP7 currently has difficulties with. They would also expose themselves to the danger or a competitor (probably Android) figuring that desktop OS is a selling point and making WP7 tablets irrelevant in the future. Remember that full Linux desktop ecosystem has more applications than WP7 currently has.