Have a MacBook Pro 2.16Ghz. 2Gb RAM 110GB HDD free running OS X 10.4.10
Have ADSL connection, no firewall, connecting at home via the same ADSL connection I have had for 3 years with no problems previously. Limewire test works.
The only difference I can see if that I use a Mac the ADSL is running off a PC. But this machine has not been changed to reconfigured at any stage so don't see how it can be the problem.