Windows 7, set to arrive on new PCs and as a shrinkwrapped upgrade on October 22, has a minimalist feel and attempts to fix annoyances old and new. In contrast, Windows Vista offered a flashy new interface, but its poor performance, compatibility gotchas, and lack of compelling features made some folks regret upgrading and others refuse to leave Windows XP. Windows 7 is hardly flawless. Some features feel unfinished; others won't realize their potential without heavy lifting by third parties. And some long-standing annoyances remain intact. But overall, the final shipping version I test-drove appears to be the worthy successor to Windows XP that Vista never was. Microsoft's release of Windows 7 also roughly coincides with Apple's release of its new Snow Leopard; for a visual comparison of the two operating systems, see our slideshow "Snow Leopard Versus Windows 7." Of course, an OS can't be a winner if it turns a zippy PC into a slowpoke or causes installation nightmares. Consult "Windows 7 Performance Tests" for Windows 7 performance test results, and "How to Upgrade to Windows 7" for hands-on advice on the best way to install it. Read on here for an in-depth look at how Microsoft has changed its OS--mostly for the better--in Windows 7.