kernel configuration

[icemaca]

hello,
i am going through the kernel configuration file to build a custom 
kernel and am not quite sure i understand this part correctly.

my cpu is an athlon 64 x2 but i am running i386, so i am assuming that 
in the config  file i state  that my cpu is i386, not athlon 64.

i ran frebsd amd64 previously, and it had HAMMER i think as the cpu in 
the config file.

this i386 version has

cpu             I486_CPU
cpu             I586_CPU
cpu             I686_CPU


Is this correct, and do i need all three?

thank you