I'm not going through XP.
I have 3 computers going through a 4 port wired router. The XP machine
connects fine. The Windows 7 machines are coming up with myriad error
messages as to why it's impossible for them to connect to the internet.
I select "make a broad band connection", it wants a bunch of username
password garbage for my ISP. I don't need that, I have time warner cable
roadrunner, you just plug in your network cable, open your browser and
you are on the internet. If I select any other network option it wants
to set up a wireless or dial up connection.
<cable> --- modem --- router --- computer #1
--- computer #2
--- computer #3
I would start by reviewing what WinXP is doing with its connection.
I can describe a scenario which would account for the symptoms, but
it would only fit for an ADSL broadband connection. If you put an
ADSL modem in "bridged" mode, virtually all other networking functions
in the modem/router box are disabled. Even though there is a switch
to provide the four wired ports, in that case it speaks PPPOE. The
WinXP machine, could detect this, and start running PPPOE itself. But
PPPOE is not a "multi-user" protocol, so once WinXP machine starts
talking PPPOE, the other 3 wired ports will appear dead.
I don't know if there is an equivalent setting for a cable modem/router
box. Namely, to disable the router portion.
I suspect the solution, is actually an issue with the modem/router.
And you're going to have to sit in front of the WinXP box, use the
administrative web interface for the modem/router, and figure out
how the router portion got disabled.
The poor computers, are only dealing with what they've been given.
If you cleverly neuter the wired ports, by using certain modem/router
settings, there's nothing the other computers can do. Microsoft, in
all their cleverness, can't burrow past the username/password on
the cable modem/router, and fix it
So, back to the WinXP machine. Log into the modem/router with
your web browser, and start looking...