When it comes to Windows 7, Microsoft hasn’t just learned from the mistakes of Windows Vista. It has picked up a thing or two from Apple’s OS X, judging by first impressions.

The executive leading Windows 7 said Tuesday that Microsoft realized it shouldn’t forge ahead on Windows 7 and deliver an operating system unsupported by partners’ hardware or software.

Also, Microsoft has heard that Windows Vista was a resource hog. The company is scaling down the code base and tickling up performance to run on netbooks and existing PCs – so no need to buy a replacement machine.

Steven Sinofsky, senior vice president for the Windows and Windows Live Engineering Group, promised we’d start to see this with the first Windows 7 beta “early next year”.

Microsoft is aiming for general availability (GA) “three years from the GA of Windows Vista”. That puts Windows 7 down for release during 2010, if you count from Windows Vista’s GA in January 2007. The word on the street, though, is to expect Windows 7 next year. Sinofsky told PDC the release date would be dictated by feedback during the beta phase.

They always say that.