Wacom companion are really good but pricey (just be careful as there is a new model coming soon), on a lower budget a microsoft surface pro 3, i would recommend to go for the core i5. Or on an even lower budget a used or refurbished fujitsu lifebook (t901, t902). All run on windows and are fully able to run photoshop, on a 13 inches display except for the surface pro which is a 12.
My vote would be for the surface pro.