A few things...
1. Windows 8 and Windows RT
are not the same thing, even though they look almost identical.
2. Windows RT is ONLY the Windows on Arm version. There is no such thing as Windows RT Pro. The product you were referring to is the Surface Pro, which will run Windows 8.
3. No Intel based device will ever run Windows RT.
4. Making things even more awesomely confusing, there is also
a separate thing called WinRT. This is the new Windows 8/RT Runtime API, and is the Windows 8 replacement for Win32 and derivatives. Both Windows RT and Windows 8 have access to the WinRT API.
5. Windows RT will run most, but not all, "Modern UI" (Metro) Applications (those that are written against the WinRT API exclusively). However, the ONLY WAY to obtain or install applications for Windows RT devices will be through the Microsoft Windows Store. Basically, think Apple's iOS App Store, because it is the same deal.
6. Intel-based Windows 8 machines will run all Modern UI Applications, and will have access to the Microsoft Windows Store.
7. Windows RT will not, ever, run a third-party desktop application not written and provided by Microsoft (and they've said they don't intend to add any new ones). This means, on an ARM-based Windows RT device, the ONLY stuff you'll ever have in the desktop environment is IE, Office, and desktop accessories like Notepad, Minesweeper, and Paint.
8. Previous versions of Windows (7, Vista, XP, etc) WILL NOT run the new WinRT based "Modern UI" apps at all.
So, what does this mean?
Well, in my opinion, it means you don't want a Windows RT device, unless all you do is surf the web (and you don't mind IE), use IMAP email, and use Office. There are essentially no apps available for them at all right now. This may change, but I'm not optimistic that it will be a very quick ramp as Microsoft seems to be suggesting. Because....
As I explained in the Surface thread, writing an application that will run on Windows on Arm (Windows RT) will require essentially
a complete ground-up rewrite. You are NOT able to target the Win32 API you've written against your whole life*. You can only write against the WinRT API, which is a limited sub-set. Applications written for the Windows Store, and therefore available on Windows RT devices, will look and feel like Windows Phone apps or Tablet apps. There will not be, ever, a "port" of an application like Photoshop or AutoCAD to the Modern UI (they may make something new for the Modern UI, and call it Photoshop, but it will almost certainly be comparable to their iPad apps, not the real desktop apps).
And, perhaps most importantly... If you are a developer with existing Windows applications and existing customers, you will need to separately continue development of your "classic" Windows applications if you want to support customers who haven't or don't upgrade to Windows 8. There is
no such thing as an application that can run on both Windows RT ARM tablets AND on Windows 7 PCs. You cannot port existing applications to WinRT. Microsoft has to approve them, just like Apple's App Store, and they require adherence to the Windows 8 Modern UI style (not to mention that the API doesn't provide for things like upper right hand close X buttons, or classic checkboxes, combo-boxes, and radio-buttons).
In my opinion, the main benefit over adopting WinRT and Modern UI versus moving to iOS development is that it doesn't require you to learn a new language, and you can re-use code that doesn't call any Windows API at all (back-end stuff and low-level modules). Also, the WinRT API is similar to the Windows 7 Silverlight Runtime API, and nearly identical to the Windows Phone 7.5 API, so if you are experienced in those development platforms, you should have an easy time. In fact, it is very easy to port Windows Phone 7 apps to Windows 8's Modern UI environment and get them to run on the WinRT API, since the WinRT API is a super-set of the previous Windows Phone 7 (Silverlight-based) APIs.
* - Except Jim, of course. Kidding!