Question : Why does "ipconfig /all" on my laptop not display a DHCP Server?

My little home network consists of a Desktop PC, a Laptop, a Netgear DS106 hub (not a switch or a router - just a hub) and a broadband cable modem. The computers both run Windows XP Professional.
My PC's motherboard used to have 2 LAN ports - one connected to the hub, the other connected to the cable modem. The laptop was connected to the hub. This configuration allowed the computers to see each other and for both to access the internet simultaneously (the laptop presumably going through the PC).

My PC has just come back from the repair shop with an "upgraded" motherboard that only has a single LAN port. I have therefore had to connect the PC, laptop and cable modem all into the hub. The problem now is that the compters don't see each other and only one can ever access the internet - the first one to be switched on.

When I use the "ipconfig /all" command on the PC, I am shown an IP address, a DHCP Server address and 3 DNS Servers. "ipconfig /all" on my laptop only shows an IP Address but no DHCP or DHS server addresses.

When I try keying in the same DNS address into my laptop's TCP/IP settings, they appear when "ipconfig /all" is run, but still no mention of a DHCP server.

Why does my laptop not see a DHCP Server address?
Where is the "DHCP server" in this simple network - my desktop PC, my cable modem, or my hub?
Is this simple "hub" connection capable of providing shared internet access or do I need to replace my simple "hub" with a "router", or get a second LAN card for my PC and try to go back to my original configuration? (I'm currently debating this with my repair shop but getting nowhere fast).

Any advice gratefully received.

Answer : Why does "ipconfig /all" on my laptop not display a DHCP Server?

According to the FAQ on page 18 of the scant documentation available for that modem (http://www.scientificatlanta.com/products/consumers/userguidepdfs/webstar_userguides/749610.pdf), it will support up to 31 devices., but does not give any specific instructions on how to do so.

I suggest setting all the computers to 'obtain address automatically', and connecting them all to the hub, using the ports 1 through 5 first.

Then connect the modem to port 6 on the hub, and set the hub's uplink switch to 'uplink' rather than 'normal'.

Shut down the computers and power off the modem (unplug the power adapter from the back of it, or its 'wall wart' adapter from the mains outlet). Wait a minute or so... power the modem back up and wait for its lights to come back on and settle down (usually takes a minute or so), then turn on the computers one by one and see if they are assigned addresses properly.  If not, change the uplink switch to 'normal' and do the shut down/power off sequence again and see if it works.

If that doesn't get it working, you may need to call your cable company's support department and ask how (which is what the modem manual's FAQ says to do). If they say it won't work and try to sell you a router, point out to them what it says in the manual on page 18. Now, if they want to GIVE you a router, that's a different story. ;-)

The disadvantage of using a hub is it divides up the 100Mbps bandwidth (that your network cards are probably all capable of) among all devices active on the network, while a switch provides 100Mbps of bandwidth to each port.  If not more than 2 devices are transferring files between them at any one time, it's not really a disadvantage... or if you're only using it to share the internet connection, that connection would need to be pretty fast for a hub to slow things down. I don't know of any manufacturers that have even made hubs in a few years, so you've probably had that for quite a while (or probably got a very good deal on it).  :-)