Here's a new word for you; Vistaphobe.
I just made it up. It's a Windows user terrified of upgrading his or her PC to Vista. Apparantly there are so many Vistaphobes out there, the PC makers are worried about losing their business. Enough so that they're willing to weasel around their agreements with Microsoft to dump XP and exclusively bundle only Vista after June 30th (a date that has been postponed since last year, due to consumer fear and loathing).
Here's how they are getting around it. After June 30th, buyers can still get a PC with XP. It will technically be a Vista- bundled PC downgraded to XP. PC makers, like HP and Dell, are taking advantage of a little caveat in their license agreements that allow "downgrade rights".
Hewlett-Packard is promising to continue selling "pre-downgraded" (I'm not the only one making up words these days) desktops, notebooks and workstations to the business crowd for another year (June 30, 2009). Dell says ditto. They're doing the same.
One other little jewel of information in all this; should you decide to bite the bullet and upgrade to Vista at a later date. No worries, you've already paid for it by purchasing a technically Vista-bundled PC to begin with.