grub inside and outside USB-Flash

['2+]

is there something i have to take into account
if i want to boot ubuntu in my usb-flash from the grub in my hda?

i forgot where but i read somewhere that i can install ubuntu to an usb-flash
just like we do to an internal hdd
so bought a 2GB flash and made it into sdb1(512M-vfat) and sdb2(1.5G-ext3)
installed a tiny cui hardy to sdb2(without swap) and also a grub to MBR of sdb

the menu.lst in the usb-flash says that the root is (hd1,1)
but here
http://www.freesoftwaremagazine.com/articles/grub_intro?page=0%2C1
it says
"You might have noticed that the root line at the top of the menu.lst
file says (hd0,0) even though we used (hd2,0) earlier. When you boot
from the USB flash memory key, the key itself becomes hd0, even before
the primary master hard drive. "
so maybe i should edit it to (hd0,1)
BUT my OptiplexGX150 doesn't have a BIOS
that can select an USB-Flash for a boot device ;-D

this is why i want to also boot it from the grub in my hda
i simply copy&pasted the original lines in menu.lst of usb-flash to that of hda
but this results into:
selected disk does not exist
editing it to (sd0,1) goes:
error while parsing number
(fd0,1) becomes:
unrecognized dev string

i found something like this:

# to boot from a usb device
title Boot USB drive
root (hd1,0)
chainloader +1
boot

but it didn't work

i should simply
grub-install /dev/hda
?

don't want to create a boot-cd for this flash

http://www.pendrivelinux.com/2007/09/28/usb-ubuntu-710-gutsy-gibbon-install/
seems to be the different way but the won't be a custom CUI one ... right?

if the BIOS doesn't do the USB-boot then grub from hda won't also boot
the system in the flash neither?

tia

-- 
'2+
http://micro.ispretty.com