32-bit Operating System V/S 64-bit Operating System

Hey Guys!
Here is an excellent topic to talk about when multiple core processors has made the 32-bit and 64-bit processors' a common talk.
Vote which type of OS [in terms of bits] will you go for... And also mention the reason!

32-bit of x86 :

The generic term x86 refers to the most commercially successful instruction set architecture in the history of personal computing. It derived from the model numbers, ending in "86", of the first few processor generations backward compatible with the original Intel 8086. Since then, many additions and extensions have been added to the x86 instruction set, almost consistently with full backwards compatibility. The architecture has been implemented in processors from Intel, Cyrix, AMD, VIA, and many others.
As the x86 term became common after the introduction of the 80386, it usually implies a binary compatibility with the 32-bit instruction set of the 80386. This may sometimes be emphasized as x86-32 to distinguish it either from the original 16-bit x86-16 or from the newer 64-bit x86-64 (also called x64). Although most x86 processors used in new personal computers and servers have 64-bit capabilities, to avoid compatibility problems with older computers or systems, the term x86-64 is often used to denote 64-bit software, with the term x86 implying only 32-bit. Today, the x86 architecture is ubiquitous among desktop and notebook computers, as well as a growing majority among servers and workstations. A large amount of software supports the platform, including OSs such as MS-DOS, Windows, Linux, BSD, Solaris, and Mac OS X. The architecture is relatively uncommon in embedded systems and low-cost niches such as appliances and toys lack any significant x86 presence. Simpler 16-bit x86 chips are more common here, but AMD's Geode and the new Intel Atom are examples of 32-bit designs used in this segment.
Contrary to some popular belief, x86 is not synonymous with IBM PC compatibility as this also implies a multitude of other hardware, albeit with some of it standardized. For instance, the original Xbox was designed around an x86 processor but security restrictions led to software requirements making it incapable of simply running standard code designed for other IBM PC compatible systems. Also, the GRID Compass laptop (one of the first on the market), and many others, used x86 chips before the IBM PC compatible market even started.

64-bit or x64 :

x86-64 is a superset of the x86 instruction set architecture. x86-64 processors can run existing 32-bit or 16-bit x86 programs at full speed, but also support new programs written with a 64-bit address space and other additional capabilities.
The x86-64 specification was designed by Advanced Micro Devices (AMD), who have since renamed it AMD64. The first family of processors to support this architecture, which AMD calls AMD64, was the AMD K8 family of processors. This was the first time any company other than Intel made significant additions to the IA-32 architecture. Intel was forced to follow suit, introducing modified NetBurst family processors, initially referred to as "IA-32e" or "EM64T" and now called Intel 64 and almost identical to AMD64. x86-64 is backwards compatible with 32-bit code without any performance loss. For example, The Developers Manuals available from Intel on the IA-32 architecture refer to IA-32 and IA-32e in tandem. AMD licensed its x86-64 design to Intel, where it is marketed under the name Intel 64 (formerly EM64T). AMD's design replaced earlier attempts by Intel to design its own x86-64 extensions which had been referred to as IA-32e. As Intel licenses AMD the right to use the original x86 architecture (upon which AMD's x86-64 is based), these rival companies now rely on each other for 64-bit processor development. This has led to a case of mutually assured destruction should either company revoke its respective license. Should such a scenario take place, AMD would no longer be authorized to produce any x86 processors, and Intel would no longer be authorized to produce x86-64 processors, forcing them back to the now-obsolete 32-bit x86 architecture. The last processors Intel manufactured which did not use AMD's x86-64 design were early versions of the Pentium 4 "Prescott", introduced in February 2004.
VIA Technologies, another producer of x86 processors, have also included x86-64 instructions in their VIA Isaiah architecture. The terms x86-64 and x64 are often used as vendor-neutral terms to collectively refer to x86-64 processors from any company.
The x86-64 specification is distinct from the Intel Itanium (formerly IA-64) architecture, which is not compatible on the native instruction set level with the x86 or x86-64 architecture.

OK...!
For me it has to be 64-bit OS. If we buy a 64-bit processor and if we buy a 32-bit OS, then its of no use even it works great! If there is a 64-bit Processor and a 64-bit OS then the Processor will be utilized fully in true sense...!

Have Fun Guys!

This edition supports the x86-64 extension of the Intel IA-32 architecture. x86-64 is implemented by AMD as "AMD64", found in AMD's Opteron, Athlon 64 chips (and in select Sempron processors), and implemented by Intel as "Intel 64" (formerly known as IA-32e and EM64T), found in some of Intel's Pentium 4 and most of Intel's later chips. It was released on April 25, 2005

I have a amd64 with a 32-bit vista and it sucks. So I loaded the 64-bit ubuntu & fedora and it rocks.