I'm using it with a Cisco wireless-g router, and a Cox provided Cisco modem. But I am using it with the included ethernet cord, if that makes any difference to you. The signal wasn't strong enough without it. In all fairness, though, I didn't try to move the extender around a bit to see if it would work better without the cord. I wanted to use my laptop with my TV as a monitor, so it all had to go in one limited space. The g-router is downstairs way on the other side of the house. The signal on my laptop upstairs went from always poor without the extender to always excellent with it. I've only just started using it, however.
Yes, it does. My Belkin N10117 is a b/g router and my "refurbished" RE1000 is faithfully extending it. The steel framing of my condominium resulted in only 3 bars in the master bedroom; with the RE1000, I have 5 bars.