"Microsoft delivers Windows Vista in both 32-bit and 64-bit flavors. While a system configuration with a x64 processor certainly recommends one of the 64-bit editions of Windows Vista, these versions of the operating system do come with downsides that customers need to be aware of. Being essentially identical to 32-bit Windows Vista, the 64-bit editions will deliver support for 32-bit applications without any problems. This aspect is one of the pillars of the transition to 64-bit. Users are encouraged to adopt
the next wave in computing technology while still being able to enjoy the same programs they used to on their 32-bit system. However, 64-bit Vista does not offer support for 16-bit applications or components. Old solutions designed for platforms that preceded 32-bit will not function on x64 Vista."
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