[syslinux] Problem with cat mbr.bin > /dev/XXX

[Ricardo Alvarez]

i've spent the last day banging my head against this one and I have no  
idea why it just simply won't work as documented.

My source system is a Sun Ultra 20 workstations running Ubuntu 7.x and  
my target system is a Dell Inspiron XPS Gen 2 Laptop. I am trying to  
to create a bootable USB Key from the VMware ESXi 3 ISO, which is an  
ISOLINUX bootable

PROBLEM:

I have a usb key (256MB) formatted FAT16 with the first and only  
partition marked bootable.
I've mounted the ISO and /dev/XXX1
I've copied the contents of the ISO to /dev/XXX1 via mount points
I've renamed isolinux.cfg to syslinux.cfg on /dev/XXX1
I've run
     syslinux /dev/XXX1
followed by
   cat mbr.bin > /dev/XXX
The target system, which recognizes that there is a USB device  
attached on boot and tries to boot from it, does one of two things:  
just hangs with a cursor in the top left corner or reports a boot  
failure.

SOLUTION:

following the same steps except that instead of doing
     cat mbr.bin > /dev/XXX
as described I executed
     dd if=mbr.bin of=/dev/XXX
the usb key is now bootable and the image loads as expected.

Has anyone else seen this behaviour?
Have i done something wrong in trying to follow the documented process?