Fastest way to make one of Linux OS (if there is more then one) to be first in grub boot menu

Boot to Your favorite Linux (if there is more then one)!

Mount all Linux OS root file systems, otherwise it may not be visible and it will not be added to grub menu (Windows visible always, despite partition mounted or not).

I want Debian 6.0.6 bigmem to be the first one (default boot OS)!

So,  open root terminal and:
# update-grub
Generating grub.cfg ...
Found background image: /usr/share/images/desktop-base/desktop-grub.png
Found linux image: /boot/vmlinuz-2.6.32-5-686-bigmem
Found initrd image: /boot/initrd.img-2.6.32-5-686-bigmem
Found Debian GNU/Linux (6.0.6) on /dev/sda2
Found Ubuntu 12.10 (12.10) on /dev/sdc2
Found Microsoft Windows XP Professional on /dev/sdc3
Found Linux Mint 14 Nadia (14) on /dev/sdc6
done

# grub-install /dev/sdc --recheck
Installation finished. No error reported.






Done!