Question : computer recognizes usb but not ethernet connection to broadband modem

I have Windows XP SP2 and have been using a Motorola modem connected to the computer by usb to access the internet for at least 6 months. I now want to use a router to connect two computers, so I tried connecting the modem to my computer by ethernet (took the usb out) and I can only get a limited or no connectivity message.

Modem : Rented a different model Motorola modem and same thing: works with usb connection, but limited or no connectivity with ethernet (also used different ethernet cable).

Broadband connection: Talked with broadband provider for an hour but they could not fix it.

Ethernet connection: Computer says that the ethernet port (Broadcom 440X 10/100 Integrated controller) is working fine.

    When I have the ethernet connection there was only packets recieved but none sent, if I remember correctly. The only ip address that I can get with this connection is the one starting with 169 which is the computer itself.  When I click repair connection, it only times-out.

(Perhaps relevant information: Initially when bought second computer I was give a D-Link switch by salesmen and told that was all I needed to have both computers access Internet at same time. After trying to link computers by switch and Windows Internet Sharing (or something like that) I called D-Link customer service and was told what the switch was for and that I needed a router.
With the switch I had an ethernet cable from computer ethernet port to switch, while the modem was connected to the computer by usb.
Have since deleted the switch connection (bridge) in Network Connections from the computer, but for a while the LAN with the broadcom was on the bridge section of the Network Connections in the Control Panel. Have now moved the LAN with the broadcom back to LAN or High Speed Internet section. Bridge section no longer exits. I also have a 1394 connection in the LAN or High Speed Internet section, too, which I assume is the firewire card I put in a few months ago.)

Answer : computer recognizes usb but not ethernet connection to broadband modem

Postpone SB4200 installation until there is no risk of thunderstorm or lightning
activity in the area.   :)   From the maual located here:  http://broadband.motorola.com/consumers/products/SB4200/downloads/SB4200_User_Guide.pdf

snerkel this is 10/100.

The top GURU here by rank (Sembee) has a website for simple tests to isolate network connectivity problems.  Give it a whirl.

Here's his reference material:  http://www.amset.info/windows/netdiag.asp

In addition to that you could try uninstalling and reinstalling the NIC drivers as well as the TCP/IP Stack to the default configuration (when the Operating System was installed).

Instructions for TCP/IP Stack reset are here:  http://support.microsoft.com/?kbid=299357

Then rerun the tests.

When you run the tests, output them to a text file for us to review.

Just like ipconfig /all > c:\ipconfig.txt above only from now on, type [command(ping for example)][paramaters] >> c:\ipconfig.txt

The commands are on Sembee's page and the >> "appends" the file so that it isn't overwritten.  This will provide us with extremely detailed information and further help to isolate the problem.

p.s.  Lost the articles, but read about other customers such as you that were assured Comcast and Motorola weren't the problem and that NICs were bad on the customer end.  You need to be working with both computers...it's rare, but possible that two ethernet NICs could be bad in two different computers.  Also, try a different network cable (as mentioned by somebody here before, but not sure if you did it).