If you have more then one PC in the house, and those PC's also communicate with each other (think shared printing, files etc) BWmeter pretty much becomes useless. -- "I reject your reality and substitute my own!"
Actually, BWMeter works very well with multiple machines on a router with a single modem. I'm using it with an Ethernet connected machine and a WiFi laptop. I've set it up so that it separates the traffic by "LAN" and "Internet".