Help. Is my RealTek PCIe broken on the motherboard?

I have a Gigabyte GA-P67X-UD3-B3 motherboard, rev 1.0. It's BIOS version is F4.

http://www.gigabyte.us/products/product-page.aspx?pid=3...

Currently, I use a Linksys NC100 network card to access the internet with this computer; however, this card does not work with Windows 7 (at least I can't make it work). I use Windows XP Pro SP3 32-bit, fully updated. My intention is to begin to use Windows 7 Ultimate 64 bit.

Unfortunately, I cannot get the motherboard's LAN to work on either XP or 7 (I have a dual boot). I have checked the peripherals section of my BIOS to determine whether or not the RealTek network adapter is working or not. It has a MAC address and is responding at 100 Mbps. The light is flashing on the back of my machine where the cable plugs in. Under network connections, it is continually halted at "acquiring network address," and I am unable to get any browser connected.

I have the latest LAN drivers from Gigabyte: 1) 5.792.1208.2011 for XP; and 2) 7.049.0927.2011 for Win 7.

Gigabyte's tech support says that there is nothing wrong with the machine aspect. I am now plugged directly into my modem. I usually use a switch because I have three computers on my internet connection. They are all gigabyte motherboards, and this is the ONLY one that is not working with the internet.

Oh yeah, as I am trying to get the RealTek network to connect, I have taken the Linksys network card out of the motherboard, to stop any potential conflict. And, as I said, I am currently plugged directly into the modem.

Am I missing something? Or is the network part of my motherboard broken?

Thank you for any help!