You cant do an upgrade at the moment as the Yoga 2 8 inch uses a compressed OS, which Windows 10 Technical preview doesn't support. I created a bootable usb stick and done a fresh install, you will need a usb hub to connect a mouse and the usb stick as the touch screen doesn't work during installation. Once installed I downloaded and installed the drivers from Lenovo's website and let Windows Update finish doing its thing. After a reboot the tablet is running perfectly