What to choose 32 or 64 bits operating system?

Today I purchased a new PC (Intel 2.4GHZ Core 2 Duo, 3GB RAM), and knowing that this processor is a 64bit processor I got puzzled if Windows XP 32 or Windows XP 64 is better for me.

So what is a 64bit system

The most important difference is the addressing size: 32bits system allow you to access up to two to the power 32 bits of addresses, that is 4GB, whereas on 64 bit systems you can address 2^64 addresses.

If you wonder what does that mean, it simply means that your application can use more memory and can work with 64bit data natively (which is an advantage over working with 32bit data).
Mostly CAM and CAD software users can benefit from this memory addressing expansion.

Can I install 32bit Windows on a 64bit Machine

Yes. 64bit machines allow you to install 32bit Operating Systems on it. For this you may install two Windows on your machine: Windows XP and Windows XP 64. Then using the OS’s boot menu you can select which OS to run.

Most applications that run on 32bits run on 64bits

Most of the 32bit applications will continue running smoothly or even at a slight speed increase under Windows 64, and this is due to the WOW64 subsystem (Windows On Windows 64-bit, used to be WOW32 on 32bits systems).
Due to more addressing capacity, a Win64 system can allocate much more physical or virtual memory than a 32bit program. It is worthwhile mentioning that on 32bit systems, the maximum usable physical memory is 4GB while under 64bits you can reference up to 128GB.

Drivers need to be present for either 64bit or 32bit

You need to realize that the WOW64 does not work for drivers. For this reason you need to have a different driver version.
Because of this your CDROM burning software will not work anymore, neither your favorite AntiVirus. You need to download 64bit enabled version of that software.

No more 16 bit applications: DOS or Win 3.1

Windows 64 does not support 16bit applications anymore. However, don’t worry, you can still use virtualization software and run your favorite old program or game virtualized.


For an excellent reading, I suggest you take a look at Charlie Russel’s white paper for XP x64 (which also
applies to Vista x64), here:
Is Windows XP Professional x64 Edition Right for Me.

Other recommended links:

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