I suppose it depends on how they calculate the 45 watt-seconds,and how efficient or inefficient the flash tubes are, but 50 watt-seconds from a Speedotron D202 power supply shot through a 65-degree reflector produces a Guide Number of 95, meaning an exposure of f/9.5 at 10 feet with ISO 100, and perhaps a two f/stops lower an exposure using a high quality, metallized silvered umbrella.
I would think that you ought to be able to make decent exposures with these umbrellas with one set 6 feet away from a person, at around f/8 at ISO 250 or so...but when you say they do not seem to be making "any visible difference", I wonder---do you have them synchronized to your camera? I don't mean to offend you by asking but, are you actually hooking one of these lights up to your camera with a PC cord, and tripping the other light with a built-in slave tripper? I mean...2x45 watt-seconds ought to make a *notable* difference over plain,indoor incandescent lighting.
Could you provide us some more details perhaps, or maybe post a sample or a link to a sample photograph?
EDIT: I looked at the specifications--do these have a PC cord connector? If not,and they depend on the camera's flash to trip the optical slaves, perhaps your camera's pre-flash could be causing a missed synchronization with the umbrella flashes. More details on your exact camera,and specific steps you have tried, would help us to diagnose your issue. I looked,and their Guide Number is listed at 90 in feet, at ISO 100, so that's an f/9 exposure at 10 feet suggested by the retailer. Something is probably not synchronized is my guess.