I'd start by checking the connections and the cable, since the most common cause of failing to obtain an IP address is connection issues. If that's not the cause, you might consider these fixes for XP-SP2.
TCP/IP stack repair options for use with Windows XP with SP2.
For these commands, Start, Run, CMD to open a command prompt.
Reset WINSOCK entries to installation defaults: netsh winsock reset catalog
Reset TCP/IP stack to installation defaults. netsh int ip reset [log_file_name]
Note: the log_file_name needs to be specified, e.g. netsh int ip reset reset.log