Ethernet Problem: Red-amberish light when cable plugged into computer

I have been experienceing problems connecting to the internet recently. My computer configuration is as follows:

 

Dell 8400, prescott P4 3.2GHZ, 4GB OCZ ram, Maxtor 160GB SATA 150 HD, ATi X300 video, soundblaster card, Windows XP.

 

I recently just upgraded from 2GB of OCZ memory to a total of 4 about two weeks prior to experienceing any problems. Windows has been going through updates and the latest batch was just prior to any problems.

 

I have been noticing that my internet connection has been a little hesitant for the past couple of months but I also just downgraded my provider from cable at 6 MB/s to DSL at 3 MB/s.

 

When I open Internet Explorer it will display that the page cannot be found. There is an option on this display to test the internet connection. When I run this test it reports that my connection is working perfectly.

 

My original HD died after less than two years and I am currently running on the second one. It is the same brand just one model newer and I bougth a new WD HD to replace it with. I installed Windows XP on this new HD and disabled my other hard drive in Bios to operate with it. With this setup it appears that there is no driver installed for the ethernet adapter. I will attempt to install a driver if I can figure out what driver I need.

 

I am a little lost on what to look for in trouble shooting this problem. I do not know how to check what type of ethernet adapter I have in order to find a driver for it. Under networks it only shows a real generic ethernet connection and not the broadcom etc.etc. etc. that I am use to seeing but this may be due to the new Windows install. The red and green lights that usually flash when a ethernet cable is installed are not lit. There is a redish amber light that is lit instead. Is this a sign of equipment failure or software? I can install a NIC card but would rather not. I also have a wireless card that I can install but again I would rather try getting the motherboard ethernet working. I am worried that my motherboard may be going out. I would rather not buy a new computer until the new Intel Quad proceesor becomes mainstream and want to get this thing running in top shape until then. Is it possible to use an aftermarket motherboard in the Dell case? The size of the Dell motherboard seems a little more squarish than most. Also, I can still run on my old hard drive if there is any advice in troubleshooting this problem out there. Thank you!

 

EDIT: 

I also want to add that I am connected to a router. I have tested the connection to the router by connecting my other computer to it using this ethernet cable. When I connect using the Dell computer the router does not see the computer connected to it.