how to setup xp without floppy and cdrom drive

So great nice tutorial.. regarding installing xp without floppy and cdrom drive..
but i encounter a problem.. the capacity of the original hhr on my laptop is
40G, i tried it first in a 10G hhd. to practice the tutorial first. it was sucessful.. but when i do it again to setup it from 40G hhd..
the screen say that "No Operating System found".. i did the same procedure,,
i tried it 6 times and yet it won't work. unlike in 10G hhd. i only did it once..
is there any limitation in formatting an hhd with fat32..
because when i format the 10G in fat32 i encounter an error that says "Too large of Volume" but i tried it again and it works.. but in 40G hhd it does'nt work anymore.. can anybody explain it to me..
Thanks in advance..