Your screen's aspect ratio doesn't really matter. Desktop apps work like they used to. "Modern" apps expand to fit the space given. The minimum resolution for such apps is 1024x768, which is 4:3.

yup, minimum to run modern apps: 1024 x 768

minimum to run modern apps with snap view (1/3 | 2/3 side-by-side): 1366 × 768

Yes, and the "snap view" feature practically demands it. They made an interesting compromise with their new Surface tablet to accommodate it. http://arstechnica.com/gadgets/2012/10/microsofts-first-stab... Sinofsky said that this [10.1" screen] made Windows' snapped view, where two Metro applications run side-by-side, too small. 11.1-inch screens solved that problem but used more power... The 10.6-inch screen is supposed to make snap view big enough while also permitting "all-day" battery life. You'll only need a 13" diagonal 4:3 screen to be as wide as a 10.6" 16:9 screen, but then you'll probably be using it from further away... So it might look awkward but you should be able to see all the content just fine.

No idea, but you could try it in a VM (it runs in VirtualBox and in VMWare as well) if you are really curious (and don't want to install it on bare hardware before it). There's beta still available http://windows.microsoft.com/is-IS/windows-8/download

> Any ideas how well it would work on a 4:3 monitor if at all?

Well, hopefully they won't do Pan & Scan. ;-)

Like all quoted resolutions, just assume it's a floor for each respective dimension.

1024 x 768 - no

1366 x 1024 - yes