As much as I like Villa, he is definitely out of the question given his transfer fee valuation. So Keane would actually make an ideal replacement. As Bro rahl pointed out, he is a proven striker in the league and has always scored goals for whoever he plays for. His off the ball running is superb and if you watch him the whole of last season, a lot of his goals came from his intelligent running. Hence, he'll provide the perfect foil for Torres. With Torres leading the line, drawing defenders, Keane who will probably operate behind Torres can use the freed space to get into the channels from balls played in by Gerrard, Barry or Alonso.
Anyway, i chanced upon this article at goal.com. Quite an interesting read about what it may not be such a good thing for Torres if Villa decides to join Liverpool.
Goal.com - Liverpool - Valencia Have To Sell Villa Or Silva - Hunter