I have used a similar product (different brand, same concept--it was Hartz brand, I think). It worked incredibly well to rid our flea infested apartment of the little buggers. I gave the cats a flea bath first, then took them to the vet, and they stayed there while the apartment was getting fogged. Covered the aquariums with shower curtains and tarps, and let the fogger do its work. We had no problems after that. Just make sure you use a flea treatment like Advantage or Frontline regularly after you fog for fleas, so you don't get a reinfestation.

Flea collars are very ineffective as I recall. They might kill an adult flea who strays toward the neck, but not the zillion feasting on the belly of your animal, or tail, or any other readily available blood source. I hate fleas!

The single best product we've ever used is Flea Busters: a borax powder pummelled into your carpeted rooms. This was used along with something like Frontline or Advantage: long lasting stuff that kills adults, and youth.) The Flea Busters will dessicate anything that dares to try to hatch in the carpet. We had no spiders, no ants, no fleas in our house for years after one application.
As far as my experience is concerned, flea collars are a waste of money better put toward something effective. Unfortunately, it sounds like the fleas might be gaining the upper hand against Frontline products. And I have no guess on what to use in an open yard where other animals might bring in fleas.