Plenty of machines have shipped with buggy drivers, poor OS support for the hardware and similar problems. I've never heard of a consumer PC manufacturer having legal liability for issues like that, and can't imagine it would be different with no preloaded OS or an explicitly unsupported preloaded OS.
The Windows 8 EULA says:
The manufacturer or installer and Microsoft exclude all implied warranties, including those of merchantability, fitness for a particular purpose, and non-infringement.
It's my understanding (IANAL) that laws in the US and most other developed countries attach a warranty to all products sold that they're suitable for sale (merchantability) and for use the way a reasonable person would expect (fitness for a particular purpose). I believe software usually gets around that requirement by being licensed with such terms included rather than sold.
I think there's a good counterargument here to the claim I often see on HN that a PC with Windows preloaded is an integrated product rather than two independent products sold as a bundle. The license terms very clearly state that the Windows part is not guaranteed to work as expected, or indeed to do anything at all. The hardware, on the other hand generally comes with a written warranty stating that it will work, or the manufacturer will repair or replace it.