XP is not user friendly connecting to the internet. If I remember correctly you can use the wizard to connect using dynamic addressing. However, it is tricky and sometimes you have to restart your router then your computer to recognize it. It might be the other way around.
If you must you can go in and instead of dynamically setting IP addresses you can do it statically by manually putting in the IP, gateway, and subnet mask.
I'd try the Internet Connection Wizard first. Again that's if I remember XP correctly.
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