Alright, I recently changed from a integrated ethernet port to a ethernet card, and so far, I can't go on the internet. The drivers are installed for the card and I don't receive as as much package as sent (ratio of 444:35). I know it isn't the router or connection because the other people can use the router, and my laptop can use wireless. My build is a Pentium D 2.8 GHz with 3.0 GB of RAM. I won't post my graphic and sound cards, since this is unrelated to internet issues (unless otherwise spoken). This isn't going to be good news, but I have a dell given as a gift from my brother, so I didn't have much say in this.
What was your goal in adding the new port? What model number MB do you have, what operating system name and version are you using? What model number new ethernet card did you install? Do either/both of the link and activity lights light up on the new port? Have you tried a different ethernet cable?