I recenty bought an 18 inch Windows tablet . . seriously.
I'd long wanted a Honking Big Windows tablet - mostly for reading in my La-Z-Boy recliner! (Hey - I'm from the USA!). Purchased a Dell XPS 18, with its most powerful processor. Officially, it is an All-In-One (all components in one thingie) and has a battery. Result - real happiness, can download & read newspapers the old-fashioned way (easily) and now read from my ginormous library of PDFs - lots of books & reports & so on. Pictures are awesome.
It's a beautiful elegant-looking thing, really, and works well in my lap. Its 5-lb weight simply is not a problem since I'm not holding it aloft. Display is wonderful, and scrolling works wonderfully well with a fingertip.
It does come with a nice stand for regular-PC-type use (thing looks like it could hold up my car if it had to), a chicklety but surprisingly nice wireless keyboard, and wireless mouse. External CD-ROM/DVD reader is optional.
Disclaimer: while it comes with 8.1, I mostly use it like I would Windows 7. With care, I can do most stuff with a fingertip instead of mouse. If I really need a mouse, I have a small clipboard I perch on my right chair arm, and then mouse away. (Yes, I do have Office 2010 installed on it.)
Drawbacks: It is not cheap, no not at all. I think this thing is a bit of a ground-breaker, but you do pay for it.
Flaws: For serious lap usage, the air cooling vents should be at the TOP, not the damn bottom. Requires a bit of care. ALSO - for use as a tablet when turning the screen vertically - the USB ports should be on the same side as the power switch! (This would enable reading files / PDFs from a USB stick without having to transfer the file to the PC itself.)
Compared to an Apple iPad (we do have an extensively used iPad), it is still the typical Windows vs Apple situation, only now there is a much handier Windows device to use. (Wife, who uses her iPad a LOT, both personally and professionally, is liking the XPS more and more, but would probably just use them both, depending on the task at hand.)
Why am I sounding somewhat like a Dell shill??? (Not - I paid full retail!!) It's because I'm not sure they know what they have here - they are marketing it as an easily transportable full PC (which it is) but not really pushing it as a Windows tablet, I think it has much potential, and it really does seem to be an elegant piece of kit that deserves some recognition.