Firefox: language packs / en_GB dictionary

[Joe Smith]

Is it expected to have Firefox install support for dozens of languages? 
Every time there's a FF update, I see a long delay and a dialog poops up 
showing many language plugins are installed.

Also, somewhere along the line, FF has switched to the en_GB 
dictionary/spelling check (based on which words it's marking). I have no 
idea how that happened or how to get back to en_US.

> $ locale
> LANG=en_US.UTF-8
> LC_CTYPE="en_US.UTF-8"
> LC_NUMERIC="en_US.UTF-8"
> LC_TIME="en_US.UTF-8"
> LC_COLLATE="en_US.UTF-8"
> LC_MONETARY="en_US.UTF-8"
> LC_MESSAGES="en_US.UTF-8"
> LC_PAPER="en_US.UTF-8"
> LC_NAME="en_US.UTF-8"
> LC_ADDRESS="en_US.UTF-8"
> LC_TELEPHONE="en_US.UTF-8"
> LC_MEASUREMENT="en_US.UTF-8"
> LC_IDENTIFICATION="en_US.UTF-8"
> LC_ALL=

Thanks for any ideas.

<Joe