My cats got fleas!

Question
My cat is primarily an indoor cat, but ocassionally we let it out to romp around.  My problem is, that every once in a while he comes back with fleas.  We've tried putting a flea collar on him, and we've tried using flea and tick oil, but neither seems to work.  Do you know what the most effective treatment is to keep fleas off of my mostly indoor cat, without making it a permanently indoor cat?

Answer
I recommend Advantage for fleas on cats.  It forms a very thin layer of insecticide all over the  skin.  When the flea touches the skin it absorbs the insecticide and it goes to the flea's nervous system.  It lasts 30 days or so with each application.  So if your cat goes outside and gets into a flea infested area, the fleas that jump on the cat will stop feeding within 2 hours and by 24 hours, they are dead.