FYI, what you're looking for is called a Tablet PC:http://www.newegg.com/Tablet-PCs/SubCategory/ID-407
I have an Asus one from 3-4 years ago that I also used for CG work. It's very nice for that and much better than having an external graphics tablet in some ways.
However, it's not as good as one would think for Windows 8. A mouse or even the touchpad works quicker and easier and using a pen on the UI made for touch just feels gimmicky. The only thing that would really work is if the Tablet PC supported touch input besides pen input. I would recommend to definitely visit a Best Buy or some such and play around with one if you are still unsettled.