Vista/Xp ICS problem

I'm at wits end with this, I spent practically all of yesterday and this
morning trying to resolve limited internet connectivity via ICS.

My Vista 64bit Ultimate notebook connects directly to a wireless
network, from which it gets internet connectivity. I can visit any
webpage and see all network devices, so things seem to be working great
on the server side.

My other computer, the ICS client, runs 32bit XP pro and is set up to
connect to the internet through my notebook. Between the two PCs is a
spare buffalo WHR-HP-G54. I can see all network devices, but it fails to
connect to most websites. It will display Google and *some* pages from
Time Warner Cable, but I cannot get to Wiki pages, my favorite forums,
or download updates for anything on my desktop PC. Based on the status
bar of my browser, which usually gets as far as "Transferring data from
", it seems the communication problem is limited to incoming streams.

I have disabled the firewall in the router that connects the two PCs,
as well as the software firewall (Comodo) that runs on my notebook but
it made no difference. The drivers for all my network cards are up to
date. I'm starting to wonder if there would be some conflict between
Vista and XP that would cause ICS to do this. Vista seems to include
IPV6 out of the box, whereas XP doesn't. I was wondering if maybe
Vista, being more modern, was trying to use a protocol or something that
my XP machine doesn't recognize.

I could get a wireless NIC for my desktop, but I already had a spare
router that I could use to connect the two PCs, so I would prefer to
stick with ICS. My cat5 cables are long enough to reach around the room,
but not to reach to the first floor where the internet-connected router
is located, a new NIC would probably cost less than a cable that long.


--
dazed_n_confused