Before everyone gets their knickers in a twist, lets be clear what's being said here:
Windows 8 on ARM systems will not run x86 apps out of the box.
Is that surprising? No. Would Apple ever try to get Mac software to run directly on the iPad? No chance! If MS did provide out of the box support for old software, would most reviewers and users complain about how poor performance is and battery life is for Windows 8 on ARM systems? Definitely - even though it's in no way MS fault.
There will be ways round this:
1) Cloud based virtualisation.
2) Server based virtualisation.
3) Hyper-V (when it's ported, which it probably will be) virtualisation.
4) Cloud-based replacements (e.g. Office 365).
Not only this, but lets face it... how many ARM computers are going to have the grunt needed to run x86 apps properly anyway? Anything with any real hardware demands will need to be re-written. CAD software on what is essentially a netbook?
Businesses and home users need to get real - if you expect to run old software designed for a single-core P3 or P4 PC with permanent mains supply and dedicated graphics processor etc on a 1GHz quad-core tablet / budget laptop smoothly without sucking the battery dead in five mins you're deluding yourself. Look at Motorola's experience with Android - 7/10 returns for Motorola handsets are (apparently) down to the user installing poorly written apps that make the phone unstable and kill the battery. And those apps are deigned to work on the hardware in question!
And let's get off this whole app thing. The big selling point of W8 is that it is universal user experience, not that it has loads of apps. Most home users won't want to run old applications on their W8 tablets any more than they'd want to run them on their smartphone. What MS are offering is the same way of accessing all your cloud-based stuff from all devices, be it Xbox, phone, PC, netbook, smartphone, virtual server session etc. Yes, lack of apps will slow sales for tablets - but I'd suggest this is short-term only and in the business sector is already more than compensated for by native support for all the MS products that most businesses already use.
So, realism is called for. MS don't help themselves, that is true, but posters on El Reg should know better. Will Windows 8 become the dominant OS on tablets? Not for a while. Will ARM become the dominant architecture on computers? Also, not for a while. Remember, the RISC / CISC debate back at the turn of the millennium? The only way ARM will ever seriously take off for productivity computing is when all those old x86 apps are rewritten or moved into the cloud - irrespective of what Windows 8 does or doesn't run.
This is not a Windows 8 issue, it's an ARM issue.