Hi,
32-bit (x86) and 64-bit (x64) refer to the width of the data path and size
of the packets that the hardware can handle. The larger the better. Right
now, most things are geared towards 32-bit (which has been with us since
Windows95). That will slowly change to x64, but there are growing pains.
The biggest issue with 64-bit at this time is not the software - most
programs will run in 32-bit mode under x64 - but the device drivers. Vista
x64 requires that all device drivers be signed, and many hardware
manufacturers are not fully on board with creating and releasing device
drivers to support the hardware on this platform. What that basically means
is that though most software will often work, some hardware will not. Since
you cannot use unsigned drivers, it's not as easy to find proper supporting
ones. It is critically important before installing x64 to check to see that
there are drivers for all of your hardware. Notably, makers of video capture
cards have been horrendous in not supporting 64-bit, keeping users of
multimedia machines from being able to use this platform.
In Vista x64, you cannot run any 16-bit applications as well, so if you are
using any of these older applications this is an additional consideration.
As well, some antivirus and utility programs use device drivers specific to
their function and you need to check that 64-bit compatible drivers are
available from the program vendor should you wish to use them.
--
Best of Luck,
Rick Rogers, aka "Nutcase" - Microsoft MVP
Windows help -
www.rickrogers.org
)