What i did to stop the most basic acces was to turn my pendrive into a 'key'

i copied /boot/* onto my pendrive

opened up th terminal

did the following

$su -c 'grub'

grub>find /boot/grub/stage1
(hd0,2)#hard dissk partition
(hd1,0)#pendrive partition

grub>root (hd1,0)

grub>setup (hd0)

grub>quit

from now on your pendrive must be plugged into the computer when you turn it on. If not you get a 'grub not found' error.

Granted this won't stop anyone with a live cd but it should stump average joe.

For more security you could delete /boot/grub/*, hide the (hd1,0) partition. etc