Starting at 12AM ET on July 29, Microsoft (MSFT) will begin pushing its much-ballyhooed Windows 10 operating system upgrade to the first line of Windows 7 and Windows 8 users who’ve registered for the download.

Not everyone will receive the upgrade at the same time–the vendor will roll the OS out in waves to compatible systems. As reported in many places, including here, Windows 10 testers will be the first to receive an updated version of the OS, the so-called Day One patch that follows a series of fixes Microsoft has been steadily issuing in the past few days immediately ahead of launch.

WinBeta reported that Microsoft completed the final Day One patch for Windows 10 with 1GB of improvements to the OS. The patch itself, which fixes last second bugs, is 500MB in size but expands to 1GB when installed.

While it’s a safe bet that Windows 10 will improve PC performance for existing Windows 7 and Windows 8.x users, will it give PC sales worldwide a much-needed swift kick in the pants? And, will Windows 10 fuel new PC sales in the important back-to-school buying period that’s already begun?

Researchers Gartner and IDC both agree that worldwide PC shipments tumbled precipitously in Q2 2015, and, while they disagree a bit on the depth of the fall, both blame stalled purchases on buyers waiting for the Windows 10 release.

Both researchers expect the PC market to right its own ship in the coming quarters into 2016. Gartner believes PC shipments will fall only about 4.4 percent in 2015 with buyers initially holding off on purchases waiting for Windows 10 and picking up the pace later in the year.

Similarly, IDC also forecasts a healthier second half of 2015 not only owing to Windows 10 but also to emerging hardware categories such as convertibles and Chromebooks in commercial and consumer markets pushing shipment totals upward.

Still, when the dust settles will users merely opt for the Windows 10 upgrade or will they buy new Windows 10-optimized machines?

Loren Loverde, IDC Worldwide PC Trackers & Forecasting vice president, suggested it may be some of both.

“We continue to expect low to mid-single digit declines in volume during the second half of the year with volume stabilizing in future years,” he said. “We’re expecting the Windows 10 launch to go relatively well, though many users will opt for a free OS upgrade rather than buying a new PC. Competition from 2-in-1 devices and phones remains an issue, but the economic environment has had a larger impact lately, and that should stabilize or improve going forward.”

PC maker Dell told the Wall Street Journal that it has about 60 million Windows 10-compatible machines in use eligible for a free upgrade. While it’s difficult to determine what percentage of those users will opt to replace their older PC rather than just upgrade its operating system, that’s where a goodly portion of the expected PC bump is likely to originate, not only for Dell but also other PC manufacturers as well.

Intro Day

As for Microsoft’s Windows 10 launch hoopla, don’t expect your basic single-location, ticker-tape parade style blowout event the vendor typically delivers for its new OS intros.

On Wednesday, Microsoft will kickoff a series of festivities for its five million Windows Insiders in 13 cities globally, including Beijing, Berlin, Dubai, Johannesburg, London, Madrid, Nairobi, New Delhi, New York, Sao Paolo, Singapore, Sydney and Toyko. Windows team members will be at some of the locations, adding to the demonstrations and hands-on opportunities.

In addition, the vendor will launch Windows 10 in 110 Microsoft Stores in the U.S., Canada and Puerto Rico on the 29th, where customers will be able to upgrade to Windows 10. Select stores will offer free in-store workshops for Windows 10 training.

Microsoft also has set up with a number of retailers to ease the upgrade process, arranging with Best Buy, Bic Camera, Croma, Currys/PC World, Elkjøp, Jarrir, Incredible Connection, Media Markt, Staples, Wal-Mart, Yamada, Yodobashi and others. The retailers will provide support for those upgrading to Windows 10, data migration services to help people move files from old PCs to new PCs, and areas where people can try out Windows 10.

And, as part of Microsoft’s year-long Upgrade Your World initiative, the vendor has partnered with 10 global and 100 local non-profit organizations to the tune of $10 million in cash investments to support their missions and promote awareness of their causes.