Self assigned IP adress on G5 won't let me connect to internet.

I received a G5 mac tower version 10.3.2. When I try to connect to the internet it won't let me and says that it already has an assigned IP address. I have tried many tips from multiple forms with changing it manually, $ infront of the password, nothing works. I have restarted my router multiple times and still nothing. Any help would be great! Thank you.