The dark clouds of Vista's delay already hang over the holiday PC selling season, and Microsoft and PC makers are trying desperately to turn lemons into lemonade with an "Express Upgrade" coupon program. But some computer companies are making their deals sweeter than others.Microsoft and PC makers really wanted to sell you a new PC with Vista installed in the all-important holiday sales period between Thanksgiving and Christmas, but since that's not happening, they've got something next-best. They'll make you a promise. If you'll buy a PC with Windows XP installed before Vista ships, they'll send Vista to you as soon as its ready. Really. Honest.

Promises, we know, are worth the paper they're printed on. But these guys are so serious they've even got a name for the program, "Vista Express Upgrade," and Microsoft has posted a list of hardware makers who'll be handing out the paper. If you're in the market for a Vista PC, you might want to make checking out the list the second thing you do before you slap down your credit card. (The first thing would be to make sure the box you're buying wears a "Vista Premium Ready" sticker, because that equally serious program means the same guys are promising you the hardware will actually run anything Vista can throw at it.)

It looks like most PC makers are charging some kind of shipping-and-handling fee for the upgrade. Beyond that, as the TV ads caution, "your mileage may vary." Sony's terms, for example, are . . . complex: If you upgrade from Windows XP MCE to Windows Vista™ Home Premium, the cost is . . . free, with a $9.95 handling fee. From XP Pro to Vista Business, free plus $9.95. But from XP Home to Vista Home Basic, $45 plus $9.95, and from XP Home to Vista Home Premium, $75 plus $9.95.

Gateway has a simpler deal: buy any Gateway PC at retail, and upgrade to a similar version of Vista for a $9.95 handling charge. Volume buyers may pay more. Depending on how good their deal is with Gateway they may pay up to $94.99 to upgrade from XP Home to Vista Home Premium -- plus $9.95.

Dell is offering something even easier. Order a Dell PC and an upgrade coupon, then after you receive your computer, redeem the coupon for an upgrade kit and pay just a handling fee (would that by any chance be $9.95?)

And if you're curious about the deal you can get from the self-proclaimed No. 1 seller of PCs? That would HP, and the Web site says check back later. They're evidently still trying to figure it out. I wonder what part of $9.95 they don't understand?

To see the entire list of companies and their Express Upgrade deals, go to here on the Microsoft.com site.