Can someone give me some closer specifications on this router's effective range? How far can it "reach", assuming that its signal has to pass through a couple of walls and/or floors? Or is this somehow related to the receiving network card and it's quality? Thanks in advance for all your help, and please excuse my ignorance.
I'm not sure anyone can give you an accurate estimate, based on what little you said. This kind of thing varies wildly depending on exact circumstances although I don't think it has much to do with the NIC that the computers on the LAN are using. Why not just get some range extenders?