For analysing network problems Etheral proved it's worth. By now this tool is called Wireshark.
But Wireshark has got a lot more to offer than simple diagnostic functions for the homebound wireless LAN. It is supporting most for the current network protocols and displays collected data by a graphic interface. Should the network be slower than it should be, you can search for reasons: Are data packages lost along the way or are requests ignored? You can even monitor USB and Bluetooth connections.
The link directed to the download of this free program can be found at the official homepage, or right here. See the changelog for detailed information.