It may affect early market share numbers for Vista, however, as some 33 percent of computers are supposedly sold during this time of year. A holiday launch would have likely resulted in the majority of those computers being installed with Windows Vista.
$10 says that computers sold during the holiday season will have some kind of voucher for free or heavily-discounted version of Windows Vista after release. They've done it before -- I want to say with 98->Me.
98 -> me, aka, "a bad move" 
This is my preference for Windows OSes in order from most despised to most liked:
98 NT 4.0 3.1 Me 95 2000 XP
As you can see, I think Me is vastly superior to Windows 98, although I think 95 was superior to both.
Any reason for 98 being at the back? It seems more common to put ME at the back, but I've never used it so I couldn't say.
Me was marginally more stable than 98 and much more functional than the other three OSes. 98 took all the great things 95 had done and broke them, plain and simple. It grew bugs like athlete's foot; over the course of only a few months a system would become virtually unusable.
I think in general, 3.1 was more usable than NT 4.0, plus you had easy access to real DOS for legacy applications.
2000 brought great strides in both legacy compatibility and moving forward technologically, and IMO XP improved in it.
