Have you scanned for Spyware/Viruses/Trojans/Worms? Any of which could be hogging bandwidth.

Do you have anything which auto updates that could be continually trying to connect?

chck your ip addressing system on your pc, seems my isp's program decided today that it was going to change my static ip address back to a dynamic...

Well for one it could be Norton screwing up your connection its a terrible resource hog and not worth the money (but thats just my opinion). Another thing with Norton is that exiting/shutting down the program doesn't necessarily turn off all its features you need to Ctrl+Alt+Delete/processes/and turn off anything to do with norton.
You don't need zonealarm running and to use it with a network you need to pay for it  and you dont always switch everything off when you disable it. Similarly with Norton you need to pay extra for use on a network.

I would suggest getting some system benchmarking software such as SiSoftware Sandra and checking your connection speed against that. It could also be that you are on a node that accepts more than the average connections this will slow the speed down at peak periods.
Connections also depend on the speed and usage of the page server you are connecting to, hence suggesting the benchmarking software.

Sorry to be fairly vague but there are so many variables with internet connections.

He has auto updates enabled so anything could sneak in during the middle of the night...............

SP2 ................. Ban the update! For instance, did an update enable the windows firewall and block your network?

Has any of your spy/virusware/firewalls blocked your network?

Try establishing a working network before setting up your security, and then narrow the security down to a single good firewall (zonealarm pro - as the free one does not support networking!) to begin with, followed by the spyware, then, if you must, the anti-virus software.

I have seen the "very slow" connection speed problem before, but it was on the client for the internet connection, and was extremely slow between host and client PC's across the LAN cable. This was resolved, I believe by setting the correct DNS server name (for the host PC in internet options on the client PC. I'm not sure if this would be similar on your router or not, so take that with a grain of salt.

P.S.  Errrrmmmm ...... is there really such a thing as an advanced networker? You know, they probably do exist, but they are kept quietly hidden away, constantly plugging away at corporate PC's, trying somehow to keep the world connected.

It's ridiculous really, the way it's all set up. I mean, what ever happened to just clicking an icon and going thru the configuration options? I guess that would be too easy...........