Issue 3: Gesture-based computing needs a better surface I was surprised to discover a third issue: the touch surface itself. I love using the touchscreen on my iPod Touch, but I usually did not like using the touchscreens on the Dell or HP.
The issue wasn't the screen per se, but its location. A monitor is in front of you, a good foot or two away. That means holding your hand and arm out, raised and extended. That's not comfortable for long durations. Try this: Move your mouse under your monitor, then see how long you can stand it. It also means a lot of ungainly arm movement to get to the keyboard, which few apps let you ignore. (Windows 7 does have a handwriting app that is OK to write with, but impossible to edit with. And writing more than a dozen words at a time is likely to make your fingers and arm hurt.)
There's also the issue of the parallax effect: The layer of glass above the LCD's crystals creates a slight gap between what you touch and what you see. At the edges of a screen, the distance is enough to throw off your hand-eye coordination -- a reason that so many iPhone users have trouble typing on the virtual keyboard's side keys such as Q, A, P, and L. Over time, your brain adjusts, of course.
The Mac OS's reliance on a trackpad for touch input lessens these issues. Your hand is at a more natural location -- on a trackpad, not the screen, so you can follow the mouse pointer easily to see where you are -- like using a mouse. And you can easily switch to the keyboard and even a second input device such as a pen or mouse. (Adesso does make a touchpad for PCs, but it doesn't use the Windows 7 gestures, relying instead on its own. I could not find any external touchpads for Macs.)
But Apple's use of a trackpad raises issues of its own. One is the difficulty of moving a relatively fat finger in a confined space, which is why Apple keeps increasing the size of its trackpads. The other is that you need to use a laptop and keep it open so that the trackpad is accessible. That's great on the road, but not at a desk. A laptop's screen is too low for most people to maintain good posture, and if you raise the laptop to raise its screen, the keyboard and trackpad placement are off. So chances are that your MacBook is closed and its trackpad inaccessible; you're using an external monitor, keyboard, and mouse instead. Sure, you can open the MacBook and use its LCD as a mirrored or extended monitor, but it's likely your desk isn't big enough to position the open MacBook, your external keyboard, and external keyboard all comfortably.