Slow Internet connection

[Paperguy007]

I know there are probably a dozen topics with this title. However, I get the feeling this case is different. I'll try not to waste your time, so I'll cut to it. I recently was handed down a macbook pro, and the internet does not function properly. Allow me to explain. Most of the time it doesn't work at all, and the rest of the time it moves at a very slow pace. Luckily, I had another macbook at hand so I could test the speed to see if maybe something was wrong with the software and the internet was working. So, I used a site to find out this information.

Macbook (Working):
Download Speed:1548 KB/s
Upload Speed: 243 KB/s

Macbook (Generally Not Working):
Download Speed: 92.9 KB/s
Upload Speed:248 KB/s

I have brought the not working one to the mac authorities six times. Replaced Airport card, antenna, and computer restored. Got any ideas?