The percentage of people in this world that know how to use a desktop OS like WIndows XP (for illustrative purposes) is very small when compared to the number of people that use consumer electronics. A tablet like the iPad, is firmly in consumer electronics territory and that's why it's selling so well. Microsoft won't likely be able to achieve this kind of success with their double-sided product.

In other words, this dual functionality is very much a geek feature, however it isn't geeks that are buying up tablet computers by the millions.

It's not a stretch to envision a near future where iOS usage eclipses the (active) Windows install base.