On all the late Fedora versions you have a choice of 32 or 64 bit
packages. If your CPU can work with 64 bit words your going to want to
use the 64 bit Fedora for a server. This is because storing on a hard
drive in 64 bit words is very much faster than doing it with 32 bit words.
Erm, sorry Karl. Wrong again.
I've never heard any claims or evidence that 32/64 bit ODs have any
impact on the harddisk access times. Someone please correct me if I'm
wrong but this is not the reason people use 64 bit OSes.
As far as I am aware there are two reasons.
1. For technical reasons, a 64 bit build is normally a bit faster than a
32 bit build, just due to compiler options. For normal desktop usages
its unlikely you would notice a difference, but it can have one if you
do heavy number crunching.
2. 64 bit OSes, have a larger memory address they can access. With 32bit
OSes the largest amount of memory a single process can use is 4G I
think. With 64bit this problem goes away. You may wonder why any single
process may need that much ram... Its true not many will but some tasks,
like large databases or image processing can get that high.
The downside to 64 bit is there are still a few bits and pieces missing.
Some propriety drivers aren't yet available in 64 bit versions, or as
most often comes up on this list, some common web plugins. This one can
be worked around by running the 32 bit web browser (64 bit linux can run
32 built binaries just fine, as long as you install enough 32 bit system
libraries along side the 64 bit ones - often referred to as multilib'ing).
If it was me, and you can live without the few missing bits and bobs, I
would go 64 bit if you hardware can do it.