Which ISP ? Which telephone exchange ( see samknows.com )
Run the speedtest at speedtester.bt.com and post the results here
Check your downstream attenuation, sync speed and SNR margin on your router and post here - see http://www.kitz.co.uk/adsl/linestats.htm
MaxDSL - goes as fast as it can and doesn't read the line checker first.
Are your kids pirates ? Limewire, Bearshare, Kazaa, BitTorrent, eMule are all tools of the trade.