If you want to use Windows, have a look at the Microsoft Surface Pro 3! I bought it some months ago. It is a tablet with absolutely full laptop performance, Windows 8 and 12 inch display. I have the version with i5 processor and 128GB. You can attach a lightweight full-quality keyboard if you want to convert it to a full laptop.
Its an awesome device, expensive, yet worth its money...
However, for using it realtime as a daw on stage, its a) to small sceen, b) not enough HD space ((VSTs these days horde memmory))
But as a desktop/laptop replacement its awesome, and also for running some smaller VSTs, or even Varranger.