Rather than keep hammering the network, may I suggest folks just look in their modem to see what speed is set:
http://root:root@192.168.100.1/P_operation.htm
Note that Internet Explorer may well baulk at the username and password in the link. For details about how to stop this happening see:
http://support.microsoft.com/kb/834489
Alternatively, just log into the modem and manually enter 'root' for both the username and password. Look under 'Operation Configuration' for the speed settings:
http://192.168.100.1/