Smartphones and tablets are booming, and their impact on health and fitness is just beginning to be felt. So which platforms should app developers target?

MyVirtualHealthCheck's announced launch of its Windows 7 version caught my eye. The app was already available for the iPhone and Android, so Windows 7 must have seemed like a natural next step. MyVirtualHealthCheck appears genuinely excited about the added functionality of Windows 7's user interface.

MyVirtualHealthCheck offers a single app for recording and sharing vital signs. It also provides access to a nutritional database and its chronic disease management website. There is even a location-based "Healthy Spots" feature that identifies nearby health food restaurants (among other healthy things).

The iPhone and Android versions are safe bets. I'm not as sure about Windows 7. Microsoft has been chasing the smartphone market for about as long as anyone—and with little success. Apple and Google just marched right in and swept everyone else aside. Microsoft's announced strategic alliance with Nokia is not so much a coup as a swan song. Nokia is the world's leading maker of mobile phones, but everyone knows that they are a has-been.