There are tablets with ARM processors and Android operating systems.
There are tablets with ARM processors and Windows RT operating systems.
There are tablets with Intel Atom processors (at 3 watts) and Android operating systems.
There are tablets with Intel Atom processors (at 3 watts) and the full Windows 8 operating system.
There are tablets with Intel Ivy Bridge processors (at about 17 watts) and the full Windows 8 operating system.
And tablets with Intel Haswell processors (at 10 to 14 watts or so) are planned for the first half of 2013 and these are for the full Windows 8 operating system.
But a couple of reviewers have complained about tablets docking to a laptop keyboard as not being rigid. The easy fix is to dock to a desktop station that could be rigid. But see when you undock your tablet and walk out the door with it, you have walked out the door with your main computer. So no one wants a tablet as their main computer but only as their travel computer. The tablet doesn't need a keyboard but only file transfer to the desktop computer. In fact someone needing a keyboard with a travel computer should just get an Ultrabook. Ultrabook ? The Samsung 13.3" Series 9 is 2.6 pounds weight and that's about the best that I can do.
As for tablets, pick your own soup but the Lenovo 10.1" ThinkPad 2 with Intel Atom and Windows 8 is about 1.3 pounds. Then the Samsung 11.6" ATIV 500T with Intel Atom and Windows 8 is about 1.6 pounds without the keyboard. But the Samsung has both WiFI and ethernet while the Lenovo certainly has WiFi and then also offers cellular.
Other tablets simply spin the tablet around and snap in place to cover the laptop keyboard. But these will always be heavy. In fact when they are very affordable they are about 3.5 pounds weight but they could possibly be 2.5 pounds like the Samsung Series 9 Ultrabook.
The Lenovo ThinkPad 2 tablet is scheduled for November 16 while the Samsung ATIV 500T tablet is scheduled for November 20. The Samsung 13.3" Series 9 Ultrabook is currently available with Windows 7.
Amazon has the Samsung 13.3" Series 9 laptop for $1200 with Win 7 (NP900X3C-A01US) or for $1300 with Win 8 (NP900X3C-A05US).
The Samsung ATIV 500T Atom/Win8 tablet and the Lenovo Thinkpad2 Atom/Win8 tablet are not yet shipping. One review of the 500T says that performance is not great (unless running RT apps) but that Photoshop works okay if not multitasking.