Why is there an MS vista that is 32 bit and a 64 bit edition? Is Microsoft not ready for a 64 bit operating system to rule the market?

In Windows XP product, Microsoft created specific Windows product editions, or SKUs, that targeted 64-bit processors from Intel and AMD. The latest, Windows XP Professional x64 Edition is the most interesting of these products because it provides functional parity with the mainstream 32-bit version of XP Professional (with a few key but understandable exceptions including 16-bit support).

The XP x64 is a surprisingly stable and well-designed product, but it was doomed to failure because of hardware and software incompatibilities: Unlike with 32-bit XP versions, many hardware devices will not work on XP x64 because of a dearth of 64-bit drivers (32-bit drivers will not work in a native 64-bit OS). Likewise, many software applications will not install or run because of various issues, including a surprising amount of 16-bit application installers and poorly-designed version detection.

The x64 versions of Windows Vista adopt all of the positive and negative quirks of their XP x64 predecessor and add a few wrinkles of their own. Like XP x64, the various Vista x64 versions support x64-compatible PCs based on the AMD-64 (Athlon-64, Opteron, Turion processors) and Intel EMT-64 (Pentium D, Xeon, Core Duo, and Core 2 Duo) platforms.

For the most part, the x64 support in each Vista edition is identical. One exception is that they each support different amounts of RAM. Vista Home Basic (and Home Basic N) support up to 8 GB of RAM, compared to 4 GB for all 32-bit versions of Vista. Home Premium, meanwhile, supports 16 GB. And Business (and Business N), Enterprise, and Ultimate all support 128 GB or more of memory. (The "or more" bit refers to the fact that there are currently no PCs available yet that suport over 128 GB of RAM; when that happens, these Vista versions will support it.)

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Karpagarajan. R
Necessity is the mother of invention