Ibook router connection difficulties

I use DSL and I have extreme difficulties getting my ibook to stay connected to my router. It seems to be related to not renewing its IP address or something, although I am not sure. It has some sort of issue with the DHCP server. I had problems initially which were corrected by disabling the pppoe extension, and then I had no more trouble. However, when I was at my boyfriend's house over the holidays, I could not stay connected to his router. It would periodically kick me off, and then the only way for me to reconnect was to put the computer to sleep, wake it up, and reconnect. I recently put in a new hard drive, with a fresh install of system 9.2, and I have not been able to stay connected at home. I get periodically kicked off, and the only way for me to reconnect is to put the computer to sleep, take out the network cable, wake it up, and then plug it back in. Today it would not respond to even that. I have tried giving it a static IP addy, which used to work in the past, but no longer does, I have rebooted three times, I have played with every available option in the TCP/IP control panel, and I don't know what else I can try. Anyone ever have this problem? How did you fix it???? I am using my housemate's compter now because I can't connect!