Not getting max Internet speed on one of my computers

We have three computers in the house, one a HP Pavilion dv6000, one HP Compaq 8510p, and one custom-built desktop.

We use to have a 1 Mbps Internet connection some time back and during that time all computers use to achieve the max speed. Recently, we got upgraded to a 16 Mbps connection on the same ISP. Now, the dv6000 and the custom-built desktop get that speed but my personal 8510p can only achieve around 2 Mbps. Note that when we were first upgraded to the 16 Mbps connection, all computers were getting the max speed, it is just recently (few weeks ago) that my 8510p can only get around 2 Mbps.

The dv6000 and the desktop are on Windows 7 and the 8510p is on Vista.

Note that there are no modems and wireless routers involved. They way the Internet works here is you take a LAN cable and connect it to the computer and then connect it straight into the LAN socket in the wall. There is a LAN connection from the house all the way to the ISP.

Also note that sometimes I would randomly get max speed on my 8510p but now it seems it is not happening anymore.

Is this problem related to my computer or ISP?

 

Update Ethernet driver and check how it works with another Ethernet cable and how it works connected to another socket.

 

Thanks for the reply. However, it turned out to be an ISP issue. I contacted them and now it's fixed.