[HAL9000]

Windows 7--unlike Vista--will probably ditch a lot of legacy code in favor of faster operation.

They make that claim about every version of Windows, but they will continue to rely on PC-DOS-era legacy code until they create a new operating system that isn't called "Windows".

[RayChuang88]

The biggest problem up till now with Windows is the fact they have to maintain compatibility with not only older hardware, but older software, too. With Windows 7, Microsoft can officially ditch any pretense of Windows 95/98 compatibility, which means the entire OS can run in the true 32/64-bit flat memory mode for maximum stability. In true flat-memory mode, you can easily "protect" parts of memory to either 1) dedicate part of the memory for an application program and/or 2) make it easier to recover from program crashes. Indeed, with Windows Vista the display driver operates in true flat-memory mode, which allows for much more graceful recovery in case of display driver problems.