Rails - Dec 2005 - text_field_with_auto_complete depending on another field

Hi,

  I have 2 text input fields.

1. City
2. Client

I want to use auto_complete on both.
As soon as you have entered the city, the list of possible
clients is much smaller.

How should I best do that?
Does anybody have an example to share?

Thanks for your help,
    -Armin