I'm using a DLink DI-713P router and US Robotics card. The range is not terrific, but it's not terrible. My room is on the opposite side of the house, and on another floor, from the router, and I get acceptable communication there. If I put it on a shelf by the door, I get pretty much constant 11mbits/s connection. If I put it on the far side of my room, it hangs around 5.5 and drops to 2 or 1 and occasionally spikes to 11. I've thought about going with an external antenna for the DI-713P but I'm still evaluating my options.
Be sure that you set the USR card to "Infrastructure" mode. I wish I'd remembered that, would have saved me a few hours.