Changing the error text

Hi,
My host seems to be having problems with one of their MySQL servers. I have been occassionally receiving this message:
Error establishing a database connection!
This probably means that the connection information in your wp-config.php file is incorrect. Double check it and try again.
Are you sure you have the correct user/password?
Are you sure that you have typed the correct hostname?
Are you sure that the database server is running?
WordPress Support Forums
I’m concerned that visitors to my site will think there’s a serious problem and not come back. Which file do I need to edit to change this message?
TIA
Phillip