And so it begins: On Tuesday, online retailing giant Amazon.com began shipping its Windows 7 preorders to customers around the globe for delivery on Thursday. But Amazon also had some good news to share with the world: Windows 7 is already a bestseller, and its preorders are stronger than the preorders for both Windows Vista and Windows XP... combined.

Amazon UK representatives were even more effusive than their US counterparts. "The launch of Windows 7 has superseded everyone's expectations, storming ahead of Harry Potter and the Deathly Hallows as the biggest-grossing preorder product of all time at Amazon.co.uk, and demand is still going strong," said Brian McBride, a managing director at Amazon UK. "Over the past three months, only Dan Brown's The Lost Symbol has sold more copies than Windows 7, which is an incredible achievement for a software product."

And compared with just its direct predecessor—the unfairly maligned Vista—Windows 7 is an even bigger smash hit: Amazon says it sold more copies of Windows 7 preorders in three weeks than it sold of Vista over three years.

As of today, Amazon and other retailers are offering literally hundreds of Windows 7-based PCs for sale. The ranks include about 30 netbook models from Acer, Asus Dell, HP, Lenovo, Sony, Toshiba, and many others. They're offered with a mix of Windows 7 Starter and Home Premium.

These are all incredibly positive signs for Microsoft and the wider PC industry, of course. But for all its positive reviews and user-friendly features, Windows 7 is entering the market at a tough time. There are still uncertainties about the economy, and many people are switching to cloud- and smart-phone-based solutions; both trends make traditional desktop OSes less viable.

That said, PC makers should still ship almost 300 million PCs over the next 12 months. And let's not forget that, even in Microsoft's most trying fiscal year, Windows accounted for almost $15 billion in revenues, $11 billion of which was pure profit. For all the silly hand-wringing over Windows, it's still a cash cow. And Windows 7 is the best version the company's ever produced, by far.

I'll be in New York this week for the Windows 7 launch, so you can expect ongoing coverage on the SuperSite for Windows and the SuperSite Blog. And if you're in New York this week, please come by the Antarctica Bar in Manhattan after 5:30pm on Thursday, where I'll be co-hosting a Windows 7 launch party with prominent Windows community members such as Ed Bott, Mary Jo Foley, and Tom Warren. See you in New York!