At Microsoft's recent Professional Developers Conference (PDC) in Los Angeles, the air crackled with anticipation. On the heels of Vista, arguably the biggest disaster in Microsoft's history, Windows 7 was about to be revealed. A blast of fanfare, and Chief Software Architect Ray Ozzie took the stage to pull the wraps off the new desktop operating system--which would deliver better performance, an improved user experience, and some nifty media-sharing features. The crowd salivated at the chance to play with Microsoft's latest and greatest.

Note: For a look at some of PC World's Windows 7 coverage to date, see:

As Windows desktop blogger for InfoWorld (a sister publication of PC World), I was drooling, too. When I got my hands on the Windows 7 "pre-beta," distributed right there at the show, I immediately installed it and began running tests. For PC World, I did an analysis of the changes (or lack of them) that consumers might see. For a deeper dive into my Windows 7 tests, check out Windows 7 unmasked on the InfoWorld site. The more I dug into Windows 7, the more I became convinced that I was dealing with an OS that was a slightly tweaked, nearly baked revision of Windows Vista.

If any pre-beta software ever called for a close look and benchmark testing, Windows 7 was it. I rolled up my sleeves and dove in. I started by examining Windows 7's innards--the kernel and other low-level structures--then slowly worked my way out to subsystem behavior and application runtime characteristics. Because one of the focal points of Microsoft's keynote presentation was improved performance, I looked for signs that Windows 7 would be faster, more responsive, and less resource-intensive than the bloated Windows Vista.

Bottom line: So far, Windows 7 looks, behaves, and performs almost exactly like Windows Vista. And it breaks all sorts of things that used to work just fine under Vista. In other words, Microsoft's follow-up to its most unpopular OS release since Windows Me threatens to deliver zero measurable performance benefits while introducing new and potentially crippling compatibility issues.

[Will your PC run Windows 7? Find out with InfoWorld's Windows 7 compatibility calculator.]

All the test tools I used for this article are freely available from the exo.performance.network Web site. You can also test your current PC for Windows 7 compatibility now, and then monitor Windows 7 performance on your own system when it enters public beta later this year, using InfoWorld's free Windows Sentinel tool.

The View From Inside

Here's what I found in the heart of the OS. Using a combination of the Windows Performance Monitor utility and some reference data I'd gathered from Windows Vista and XP, I began comparing the runtime structure and composition of various OS processes and services.

First up was the Windows 7 kernel--aka the System process. When comparing Windows versions, it's always good to start with the kernel because this is where the most fundamental changes take place. For example, when Microsoft went from Windows 2000 to Windows XP, the System process gained 21 execution threads in its default configuration. Likewise, when Microsoft introduced Windows Vista, the kernel gained 39 execution threads.

[What's so wrong with Vista, anyway? See "Death match: Windows Vista versus XP."]

In fact, the kernel in each major new version of the Windows OS has spawned a different, typically higher number of threads. So when I examined Windows 7 and found a nearly identical thread count (97 to 100) for the System process, I knew right away that I was dealing with a minor point-type of release, as opposed to a major update or rewrite.