Do you know more about your friends computer? Like the CPU it has or Motherboard? Unless you're sure it's a "PCI Express" socket, off course. Also, what kind of PSU (power supply) does he have?
In that case, to play MW1 (or even the 3rd one), the cards you suggested are plenty for medium + settings.
I can't look at newegg at the moment to give you a better assessment, but I'm sure other folks will kindly link you some cards.