Would you rather have a small iPad or a computer on wheels (COW)? You can actually have both by docking an iPad into a cart that has a keyboard. The challenge right now comes with using the mouse since the current iPad (or iPad 2) doesn't support a mouse. You can easily attach a Bluetooth keyboard and type away, but the mouse function requires some "hacking" (jailbreaking). I don't see many hospital IT folks eagerly jailbreaking iPads.
Eventually, as slate tablets evolve, they probably will support pointing devices like mice. Then, the COW experience could truly be replicated by using a small slate tablet like the iPad in the clinical setting.
Today, you can use a slate PC running Windows 7 on a cart so that you can effectively have a slate tablet + COW combination. We're seeing many more slate tablet PCs running Windows 7, so maybe that will eventually become the standard in the hospital setting.