We're now exactly two weeks away from the release of Microsoft's (NASDAQ:MSFT) highly anticipated -- and, quite frankly, necessary -- successor to its Vista operating system, and the company's reputation could hinge in part on its success.

Early buzz has been generally favorable for Windows 7."I believe it is the best version of Windows Microsoft has produced," influential tech columnist Walt Mossberg writes in this morning's Wall Street Journal. "It's a boost to productivity and a pleasure to use. Despite a few drawbacks, I can heartily recommend Windows 7 to mainstream consumers."

Mossberg has been historically partial to Apple (NASDAQ:AAPL), so when he concludes that it's "much more of a toss-up between the two rivals" with Windows 7, that's as ringing an endorsement as one is likely to find.

Apple on the attack
I doubt the effective "I'm a Mac" ads will end, though. There are still weak spots in Windows' armor that the Cupertino giant will likely exploit: 

  • Windows 7 may be a reasonable upgrade process for Vista users, but it could be an outright chore for Windows XP users, who still make up the largest base of Microsoft-powered machines.
  • For efficiency's sake, Windows 7 doesn't ship with built-in programs for photo cataloging and video editing, contrary to what was available in earlier editions. Those extras will now be available as free downloads, but Apple can have still a field day pointing out its own candy-store of preinstalled multimedia goodies.

It's also possible that some of Windows 7's flaws will be exposed once the platform is out in the wild.

"The test feedback has been good, but the test feedback on Vista was good," CEO Steve Ballmer warned in a Bloomberg interview last week. He's certainly not the sugarcoating salesman that Steve Jobs can be, but there's nothing wrong with guarded optimism.

Ballmer knows that the battle is long, and that Windows 7 isn't perfect. He also knows that Apple will do its part to point out any weaknesses. And when Apple goes on the attack, it usually does so with great efficiency.

Buy Dell and HP
The mostly good reviews on Windows 7 may be blessings to the hardware and software companies that will rely on the operating system.

Hewlett-Packard (NYSE:HPQ) and especially Dell (NASDAQ:DELL) will be the biggest beneficiaries if the upgrade path from XP to Windows 7 is a monstrous headache. Instead of upgrading to Microsoft's new operating system, many computer owners will choose to simply back up their data files and move on to a new machine with Windows 7 installed.

The lack of preinstalled goodies should also benefit Adobe Systems (NASDAQ:ADBE), Sony, and smaller software companies that make video-editing software. Even if Windows Movie Maker is just a free download away, users who never figure that out will seek out third-party solutions, as will all the folks who believe they've outgrown Microsoft's rudimentary freebies.

The times, they are a-changin'
The one reason to tread carefully if you're a Microsoft investor -- or even a potential shareholder -- is that this could be as good as it ever gets. Even if Windows 7 is the shovel that buries the ill will over Vista, it also may be Microsoft's last great operating system.

Whatever Microsoft cooks up as a successor to Windows 7 in a few years is unlikely to be as relevant. Smartphones, tablets, and netbooks are redefining the computing experience, and the browser is becoming as important as the operating system.

Even Google (NASDAQ:GOOG) is diving into the operating-system space. And who would be shortsighted enough to deny the evolutionary possibilities of Palm's (NASDAQ:PALM) webOS, or whatever Marc Andreesen is cooking up?

If cloud computing is the future, operating systems will be far more interchangeable, and far less relevant, than they are today. That would be bad news to both the "I'm a PC" guy and the premium-priced "I'm a Mac" peddler.

So look for the relief that Oct. 22 brings, and enjoy while it lasts.

Will Microsoft be less or more relevant in a few years? Chime in with your opinion in the comment box below.

Microsoft and Dell are Motley Fool Inside Value picks. Google is a Motley Fool Rule Breakers recommendation. Adobe and Apple are Motley Fool Stock Advisor picks. Try any of our Foolish newsletter services free for 30 days.

Longtime Fool contributor Rick Munarriz is gradually tiptoeing into cloud-computing apps, and he likes it. He owns no shares in any of the stocks in this story and is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.