Debian :: Set Default Character Encoding In Gnome-terminal?

I try to change the default character encoding in gnome-terminal. I want to use UTF8, but every gnome-terminal i start uses "ANSIX3.4-1968".

In the menu, when i go in Terminal => Set character encoding i have a list with two items:
[x] Current Locale (ANSIX3.4-1968)
[ ] Unicode (UTF-8)

I don't know why the first item appears, i have another debian box and it has only the UTF-8 encoding available. I cannot remove the first item in "add or remove" sub menu !! Probably because it is related to "current locale"

Here is the output of "locale", if it can helps:
boulzor@antec:~$ locale
LANG=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"

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