booting from fat32 partition or rootfs

I am Manish and i am new to working with beagleboard xm.
I am using a SD card with 2 partiiton in it namely. boot(fat32) and
rootfs(ext3).I have observed that it is possible to boot the BBxm
using the uImage from either boot or rootfs.

Which is method is advisable and what are the advantages??

Manish Kanchan