OK try the following:

Click Start > Control Panel > Network Connections. Hightlight the Local Area Connection. Right click and select Enable. If you only have the disable option try disabling it first then re-enabling it. If that does not work right click and try repair.

If all that fails then we can try setting the ip address manually.

If from your example above the router's ip is 192.168.0.100 then try the following:

In the Network Connections as per above right click Local Area Connection > select properties.
Scroll down through list - double click Internet Protocol (TCP/IP)

Select Use the following IP address: type the following into the corresponding fields:

IP address: 192.168.0.75
Subnet Mask: 255.255.255.0 (this should autocomplete for you)
Default Gateway: 192.168.0.100 (or whatever the ip address of the router is)
Use the following DNS server addresses:
Preferred DNS Server: Same as default gateway. Click OK.

Test connectivitity. If this doesn't help try changing the ethernet cable and setting the TCP/IP settings above back to obtain ip address automatically. If the routers ip address is different from 192.168.0.100 e.g. its 10.0.0.1 then let me in your next post.
One other thing - if you go to Start > Control Panel > System > Hardware Tab > Device Manager is anything listed with a yellow exclamation mark? If so please post back, if this is the case do you have a separate network card or is it onboard - please post back with either the motherboard make and model or the Network adaptors make and model.

I think the Router is bad because I tried it on another computer and got the same result I don't think both computers would have a problem.
This router I got from e-bay and it was not new so I am going to get another brand router.

THANKS FOR YOUR HELP

NP - sorry we couldn't get it up and running. Your right it does sound like the router if more than 1 pc are having problems. If your looking at getting a new one then I'd recommend a Netgear or Linksys.

One last thing I wanted to ask - did you try resetting the Dlink back to factory default. The person who owned it previously may have disabled DHCP. If not then try it - it just may work. Make sure there are no cables plugged into the router
To reset it - power off the router
Press and hold the reset button
Power On > Keep holding reset button for approximately 5 seconds.
The M1 and M2 lights will flash 8 times and then m1 will flash once per second.
Make sure pc's are set to get ip address via DHCP.

Also don't plug the router into your modem just yet - just plug one of the pc's directly into one of the 4 ports on the front of the modem and nothing else. Check IP setings with ipconfig as per previous post. You may need to reboot the pc. If you now have an IP address and default gateway (it'll probably be 192.168.0.2 or something like that) then the router is working. Post back if you would like anymore help.

George I think it maybe dead.As I said earlier in the thread the UK discontinued that model.