Vista - VISTA Home Premium HP Pavilion a6120n, Limited or No Connectivity wired network

I recently bought a HP Pavilion a6120N and realized that the Manufacturers warranty had expired.
When I switched it on for the first time, after a lot of setup time, I found that the wired LAN was not working.
My internet setup is as follows -
Cable Modem => DLink VWR router (vonage phone adaptor and wireless router) => Basement to First Floor Cable connected to one of the Ports => from First floor wall to HP Desktop.

After restarting my DLink router, the HP desktop internet worked fine.
Then it said that it had some updates for Norton. After installing the updates and rebooting the desktop PC, it started showing up Limited or No Connectivity in the desktop icon.

I uninstalled Norton completely and then tried rebooting but of no use.

Previously I had a Compaq desktop with XP Pro installed and everything worked fine. It is the same connection that is failing to work. Also, I tried connecting to a laptop IBM T61 with XP Pro and it works fine.

Can someone help solve this HP Pavilion Desktop with Vista Home Premium network issue.