If typing at your desk is starting to make you feel uncomfortable, you need the Surface Ergonomic Keyboard. Its curved shape and wrist rest should solve your comfort problems quickly.
The Surface Ergonomic Keyboard is an upgraded version of the standard Surface Keyboard, but design changes make it more comfortable to use for hours on end. A curve in the center of the keyboard deck, breaks up the keys and forces you to adopt a more natural position for your hands as you type. The Alcantara wrist rest on the bottom of the keyboard prevents wrist and hand strain. This wrist rest gently rises to the keyboard's level, so it isn't as awkward as the large gel wrist rests that office supply stores sell.
If you have a hard time reaching up to use the row of number keys, buy the Surface Ergonomic Keyboard and abandon them. The keyboard has a dedicated number pad on the far right. Arrow keys and command keys sit between the keyboard's letters and this number pad.
Amazon sells the Surface Ergonomic Keyboard for $107.66. Bluetooth technology allows the keyboard to talk to your PC, so it doesn't come with a receiver.