Re: Apple 2?
Windows 7 Starter is already like this - AFAIK you can't buy it on its own. Whilst things will perhaps become more significant as it rules out building say an ARM desktop, it's not closed in the Apple sense (where you can only buy hardware from Apple), and since this is targetted at ultra-portable/netbook/tablet type machines, it doesn't seem to me a problem that you can't buy it separately.
The bigger concern as far as being closed like Apple is the idea that WinRT only runs Metro applications (except for Office), and if these can only be distributed via Microsoft's site.
I do wonder if WinRT PCs will end up replacing current x86 netbooks, in the sense of being low cost portable PCs. On the one hand, it seems a good thing to improve netbooks with touchscreens, make them even lighter, and give them even better battery life, and perhaps ARM is more suited to that than Intel Atom. On the other hand, I like having x86 compatibility in a netbook, and would still want to be able to run windowed applications rather than just Metro. So it would be a shame if the options for x86 low cost ultra-portables/netbooks dries up, meaning our only option is to spend far more on the high end ultra-portables. If MS don't have a low cost "Starter" version of Windows x86, and instead only do for Windows RT, then that will make it even more likely this change happens...