's a look at how the screens stack up. All measurements reflect the diagonal length of the screens:
— 10.6 inches: Microsoft's Surface, running its Windows system. That's the size for both the full-powered version, which runs standard Windows applications, and the lighter Windows RT version, which runs only apps designed for tablets. The RT version starts at $499 and comes out Friday. Microsoft hasn't disclosed price and availability of the heavier one.
— 9.7 inches: The full-sized iPad, from the original model on. Starts at $399 for the 2011 model. New model out Nov. 2, starting at $499.
— 9 inches: Barnes & Noble Inc.'s Nook HD+, coming out Nov. 1, starting at $269.
— 8.9 inches: Larger version of Amazon.com Inc.'s Kindle Fire HD. It will be out Nov. 20, starting at $299.
— 7.9 inches: iPad Mini. Starts at $329. Out Nov. 2.
— 7 inches: Smaller versions of Kindle Fire HD and Nook HD, both starting at $199. Non-HD version of Kindle Fire available for $159. Google Inc.'s Nexus 7 also starts at $199.