First, we ran the tests when the computers were placed at a distance of 5m from each other in one room.
In this case, the connection quality is close to the ideal, with the data-transfer rate being over 700KB/s. Of course, a wired network provides much faster transfer rates, but the bandwidth you have with 802.11b cards is quite enough for surfing the Internet or playing a network game.
In our second test, we moved one of the computers into a next-door room. The beeline distance between the antennas of the network cards was 15m. Moreover, they were separated by one plasterboard and two concrete walls.
The signal power grew considerably worse. However, our network maintained acceptable data throughput even under such unfavorable circumstances.
And the last note. The WiFi slot available in all new mainboards from ASUS will be compatible with the upcoming network cards from ASUS. Particularly with 802.11g ones.