Hello fellow Strobist!
I own a set of poverty wizards as well (1 transmitter, 2 receivers). I plugged the transmitter into the hotshoe of my Pentax K100D. I have used a Metz 48 AF-1 and a Sunpak 422D with this system. I'm no advanced lighting user, but it works for my needs. Granted, I'm limited to the 1/180 sync speed, but I usually don't need to go faster anyway.
I don't have any umbrellas yet, but I plan to, as I already bought some light stands on eBay. With the Cactus triggers, the flash ends up a bit too high to properly position the light on the center of the umbrella. Therefore, if you're going to use a flash wirelessly on an umbrella, either get a flash with a sync port, or get a TTL hotshoe cable (the Pentax flash extension adapters/cables work as well).
In terms of range, your mileage WILL vary. My units are decent; I can trigger flashes located downstairs while upstairs across the room. Others won't be as lucky. To improve performance, others have performed antenna mods that have improved the reception range to Pocket Wizard ranges.