I am trying to share a cable internet connection between two computers. I have linsys network hub with an uplink port. I hooked it all up, and one of the computers can connect fine, but the other cannot. Both computers are running win xp.

I think we need a little more info on how you have these wired. I *think* you have the modem connected to the hub and both of the computers connected to the hub. That would explain why only 1 computer can connect. If you have one PC with two network crds, then you could do it with ICS (Internet Connection Sharing), but hte better option would be to get a Router.

the modem is connected into the uplink port in the hub. I thought that a hub with an uplink port worked like a router. Is this not true?

also, we have isolated the problem to one computer, because even when the working computer is not connected, the not-working computer wont get the internet connection. So could it be something with the network setting. We set obtain ip address to automatically, is that correct? Thanks for the help.

"I thought that a hub with an uplink port worked like a router"

A hub is a hub
A router is a router
A switch is a switch

You need a Router, and set your PC's to obtainn an address automatically as the router will act as a DHCP Server.

plainandsimple is correct. An uplink port on a hub is so you can connect the hub to a switch or another networking device with a straight-through cable as opposed to a cross-over cable.

"we have isolated the problem to one computer, because even when the working computer is not connected, the not-working computer wont get the internet connection"

I believe the ISPs can use the MAC address to verify the machine requesting an IP before giving it out. Every network device has a unique MAC address that is hard-coded into the device. So, if the ISP is using the MAC address of your 1st computer to verify the machine, then you will not be able to get an IP with the second machine - even if the 1st machine is not connected. However, many (if not most) routers come with the ability to "clone" a MAC address. Just clone the MAC address of the first computer into the router and your ISP will see the router as that computer and give it an IP.