Yes, that could possibly help. If you right click on My Computer and select Properties. On one of the panels you will be able to change it. Sorry I am at work an don't have an XP machine in the office.
Don't think it's the nic card but you could test it by yanking the one out the other machine and trying it.
Have you checked all the TCP/IP settings to be sure it's trying to get the IP automatically. Did your Workgroup name change?
About changing your user name please see this thread.
As for the time zone the server is set to I don't have that answer but can find out. But it may depend on which data center you are located in. What server are you on?
And welcome to the family, James!