help! fleas

OK, first of all, since we used the crummy poisonous and non-working Hartz it didn't kill the fleas that my friend's dog brought into the household, so now I think (haven't been down there yet) the cat room downstairs must be infested.

Mercy is FINALLY recovered from her poisoning from the Hartz garbage, and supposedly they are to be flea free from this stuff but it's apprently not working as described and I'm going to have to do something else to get the fleas under control. Yikes!

I have used Advantage (the right stuff - from the vet) on them all and they are all doing ok, nobody is sick from it, but dang it! tonight I saw a living flea on Molly! She's getting them from somewhere. They are easiest to see on Molly because she is snowy white.

I'm disgusted and scared, but I think we're going to have to spray or fog the house.

Meanwhile, my poor little kitten Byzzy is in an Elizabethan collar tonight because she has a big goose egg around her incision from her spay operation last week. We took her to the Pet ER and they gave her some pain meds and the collar so she can't lick it tonight and she is freaking out over the collar, refuses to calm down. They said the doc who did the surgery needs to check her out and they think she has an absess or broken wall where intestines might be coming through her incision! Yuck!! Poor little thing. We are going tomorrow to get her checked out.

But my question is really about the flea control. Now that they have had Advantage and some fleas are still living on them, that means there is a source of new living fleas and we need to KILL them or we will become just more and more infested, right?

So now - what is the right thing to use that is safe for people and cats???

I'm at my wits' end. I've had a flea infestation once before and it took a lot of physical labor to clean it out I am not able to do that. I can't even get down the Stupid stairs to go and see what and where the problem area(s) might be.

When I ask DH he just tells me 'it's pretty bad' which for him could mean the fleas are marching up and down like an army ready to spring on any unsuspecting warm blooded creature.

I'm getting really worried and I truly don't know what to use. Please help with any ideas or experience you have had.

Thanks
Janie