Fleas on 13 w/o puppy

Question
Okay, I need some help here:

I have a 13 w/o German Shepherd.  I live in a house with my roommate and her 1ish year old Golden Retriever.  My roommate "adopted" her dog off of the side of the road a few months ago, and has never really treated him for fleas, ticks, etc.  I believe her dog has been bringing fleas into our house, and now my puppy has them.  I have tried flea baths (marked safe for puppies, of course), but they only provide temporary relief.  I am taking my dog to the vet tomorrow to get some medicated drops that kill/prevent fleas, but I am unsure as to how to treat the house safely.  Also, my roommate will not treat her dog because she does not belive that he has fleas.  I know that the fleas will return shortly if they are not all killed, so how can I get rid of them on her dog?  Would a flea bath solve the problem if the house and yard are treated for fleas?

Sorry if the post is confusing, I am a little flustered and in the midst of my finals this week.

Answer
We've gotten fleas here a couple times over the years, and really, the easiest way to eliminate them is to simply treat the dogs. We used Advantage and it was quite effective (it can be used on puppies over seven weeks old), although it took about three months to kill off all the fleas since we only treated the dogs. Personally, I didn't want to treat the house for fear of getting any poisons on us.

Diatomaceous earth sprinkled inside and out is supposed to kill fleas without subjecting people to harmful toxins.

Here is a great link to everything about fleas: http://www.fleascontrol.com/natural-flea-control.htm

I can't believe your roommate can know that your puppy has fleas and still believes that her dog does not! I guess you will just have to find a flea and/or flea dirt on her dog to prove it to her.