How do I set the UI language in vim?

I saw this on reddit, and it reminded me of one of my vim gripes: It shows the UI in German. Damn you, vim! I want English, but since my OS is set up in German (the standard at our office), I guess vim is actually trying to be helpfull.

What magic incantations must I perform to get vim to switch the UI language? I have tried googling on various occasions, but can't seem to find an answer (No, Google, you're my friend *pat*, *pat*, but I allready know how to change the syntax highlighting, thank you!)...

EDIT: Using all the good tips below, I ended up adding this to the top of my .vimrc (running Vim 7.2 on Windows 7)

set langmenu=en_US.UTF-8    " sets the language of the menu (gvim)
language en                 " sets the language of the messages / ui (vim)

Solution 1:

For reference, in Windows (7) I just deleted the directory C:\Program Files (x86)\Vim\vim72\lang. That made it fallback to en_US.

Solution 2:

Try this in _vimrc. It works with my win7.

set langmenu=en_US
let $LANG = 'en_US'
source $VIMRUNTIME/delmenu.vim
source $VIMRUNTIME/menu.vim