Rails - Aug 2006 - Two Autocompletes, make first value affect the second

I have two  text_field_with_auto_complete
text_field_with_auto_complete :user, :state
text_field_with_auto_complete :user, :suburb

The user fills in the text_field_with autocomplete... but then I want to
filter the results in the suburb with the value they''ve just entered
def auto_complete_for_user_suburb
    @suburbs = PostCode.find(:all,
      :conditions => ["lower(locality) LIKE ?",
''%'' +
params[:user][:suburb].downcase + ''%''
	AND state LIKE "WHATS IN STATE FEILD"	
],
      :order => ''locality ASC'',
      :limit => 12)
 
    render :partial => ''suburbs''
  end

my problem is that I can''t work out a way of delivering the text_field
:state contents to the auto_complete_for_user_suburb function.  

Any ideas?