Simple logic/structure question

Curently I have this code in my controller:

  # sort by letter or by cuisine and letter
  def by_letter
    if params[:c].nil?
    @restaurant_pages, @restaurants = paginate_collection
Restaurant.find_by_letter(params[:letter], params[:sort]), :page =>
@params[:page]
    @cuisines = Cuisine.find_all
    else
    @restaurant_pages, @restaurants = paginate_collection
Restaurant.find_by_cuisine_and_letter(params[:id], params[:letter],
params[:sort]), :page => @params[:page]
    @cuisines = Cuisine.find_all
    end
  end

Which decides what to do based on a string that is passed as a
parameter to the action. The model then has two methods corresponding
to the if and else clauses:

  # restaurants that begin with a number
  def self.find_by_number(sort)
    Restaurant.find(:all, :conditions => ["name REGEXP '^[0-9]'"],
:order => (sort || "name"))
  end

  # restaurants that belong to a specified cuisine and begin with a
number
  def self.find_by_cuisine_and_number(cuisine, sort)
    Restaurant.find(:all, :conditions => ["name REGEXP '^[0-9]' AND
cuisine_id = ?", cuisine ], :order => (sort || "name"))
  end

My question is would it be better to pass the string to the model and
then have an if statement that decides what the condition should be?
This would mean less code repitition as the two methods above would be
one shorter method. Thanks for your help. Feel free to ask any
questions regarding the application.