There's no question that Microsoft's decision to build its own tablets changes the market considerably. But until we know more-precise details about specs and pricing, accurately predicting how well the two Surface models will compete is quite difficult.

In the end, the Surface RT may not quite be an iPad killer. Apps are paramount to tablet buyers, and until we see what kinds of Metro apps Microsoft and its developer partners produce, many consumers may shy away from the Surface RT.

Surface Pro, meanwhile, will challenge the current crop of laptops and Ultrabooks--and there it may well win. Why purchase a classic clamshell-style laptop if you can get a tablet that quickly and elegantly becomes a laptop when you need one--all without sacrificing performance, interoperability, or functionality? The big question here is whether consumers can manage with a 10.6-inch display as their laptop screen; for many consumers, I suspect, the convenience of a tablet/laptop hybrid may be worth the drawback of having to put up with a smaller screen.

If not, just wait: No doubt Microsoft's hardware partners are kicking plans to design Windows 8 tablets of their own into high gear--including models with bigger screens--to compete with the Surface Pro.