Opinions are split over Windows 8. Some love it, some hate it. But even the former group isn't buying much simply because many of the most promising Win8 systems just can't be had -- a fact that, more than any technical or esthetic consideration, threatens to derail Microsoft's new OS.

Windows 8 and related hardware launched Oct. 26. To date, Microsoft has been mum on sales data, with the exception of Windows unit co-chief Tami Reller's claim last month that 40 million licenses have been sold. The number is meaningless, given that Microsoft has refused to say how many of those copies are preinstalled on systems that have yet to find a buyer.

Estimates from more objective sources paint a dismal picture of Windows 8 hardware and software sales. Market researcher NPD last week said that sales of Windows-based systems are down 21% since Windows 8 debuted on Oct. 26, compared to the same period a year ago.

[ Check out 10 Great Windows 8 Apps. ]

That's surely disappointing for Microsoft and its partners, but the operating system's relative merits are only one part of the story. The fact is, many of the most promising Windows 8 systems haven't made it to market yet. Some have been delayed until next year.

I've written before about Microsoft's inexplicable decision to hold back Surface Pro, which runs Windows 8 Pro and supports legacy applications, until after the holidays. That means buyers who want a Surface right now are stuck with Surface RT, a $499-and-up device that can run apps only preinstalled by Microsoft or downloaded from the somewhat limited Windows Store -- no Facebook, no Twitter, no LinkedIn.

Small wonder Surface RT unit sales are projected to come in at well under a million in the current quarter, according to analysts at brokerage Detwiler Fenton. (By contrast, Apple sold three million iPads in three days following November's launch of the iPad Mini.

But it gets worse. Windows 8 tablets and convertibles built around the platform that was supposed to put Win8 on an even footing with the iPad and Android are scarce. That platform is the Clover Trail version of Intel's Atom architecture. The chip is designed to deliver energy efficiency and battery life on par or better than ARM chips, and the power and legacy compatible of x86 systems. Vendors pitched their Clover Trail-based products as devices with no tradeoffs.

Is that really true? Hard to tell, because you're about as likely to find Clover Trail tablets and convertibles on store shelves or online as you are to find Sandra Fluke at a Tea Party convention.

Here's the current availability of Clover Trail systems from the top five PC vendors, in no specific order. The ASUS Vivo Tab Smart? No launch date specified. The Lenovo ThinkPad Tablet 2 is "coming soon" according to the company's website. As of Friday, an order placed on Hewlett-Packard's website for the Envy X2 Windows 8 hybrid tablet/PC will be fulfilled on Jan. 7. It was supposed to launch Nov. 14. Dell's estimated ship date for the standard version of its Clover Trail-powered Latitude 10 tablet is Dec. 28; for the enhanced version it's Jan 4.

The only Clover Trail system I could find that's available for immediate purchase is Acer's Iconia W510 tablet. A Microsoft rep confirmed that it can be had directly from Redmond's online store, but purchase quantities are limited to one. As of Friday, Amazon had exactly 18 units left of the $749 version that comes with keyboard, and was sold out of the standard, $599 version.

This situation has to be absolutely killing Windows 8 sales. To be sure, there are some nifty Intel Core-based Windows 8 convertibles and tablets out there, like the Dell XPS 12 and the Acer Iconia W500, but they're typically priced $800 and above -- unlikely to make them big holiday sellers. Windows RT systems, such as the Surface RT and ASUS Vivo Tab RT, are price competitive with the iPad, but don't offer nearly as many quality apps to choose from.

Clover Trail systems, on the other hand, seem to hit the sweet spot in price, performance, application availability and compatibility. "At a retail price of $500, this device is a better value than most other tablets since it can run x86 programs and still last as long," read an Iconia W510 customer review posted on the Microsoft Store. But supplies of Clover Trail systems are short or non-existent.

Sources tell me the delay rests with Intel, which is having trouble producing production-quality Clover Trail chips in high volumes. No doubt hardware makers who built holiday marketing campaigns around Win8-on-Clover Trail systems are seething. Is it any wonder Intel CEO Paul Otellini is stepping down? Is it any wonder that Microsoft has suddenly gotten serious about building its own hardware?

Upgrading isn't the easy decision that Win 7 was. We take a close look at Server 2012, changes to mobility and security, and more in the new Here Comes Windows 8 issue of InformationWeek. Also in this issue: Why you should have the difficult conversations about the value of OS and PC upgrades before discussing Windows 8. (Free registration required.)