Wireless connections CAN work well, but if they don't they can complicate matters tremendously. They are inherently not as secure.
To use an iPad, you are crossing operating systems from iOS to Windows, thus you would have to use logmein or some other remote desktop program. While they are good, they are not as fast as running natively in Windows.
Laptops can work, but laptops and iPads have a higher likelihood of being stolen. They also cost more than a desktop system and probably do not quite have the lifespan. Repair costs are higher as well.
Thus, hardwire (gigabit lan is much faster) systems with desktops in every room is the most frugal, secure and lowest maintenance method. It does take up additional real estate and theoretically you cannot face the patient as easily (turn sideways works.) It's not as high tech as walking in with a tablet, but ....
There may be some Windows 8 tablets on the horizon that may work. But they are not available at this time.
