Windows Vista and a connection problem

I am new to Vista. Fact is - I never worked with Vista until I was sent on a call for a National chain to a persons home that could not connect to the Internet with Windows Vista. The call was to replace the motherboard due to faulty on-board ethernet port. I replaced the motherboard and still had the same problem. So here is a little more info: private network - 10.x.x.x (that connects via satellite system). A laptop with XP CAN connect to the Internet through this same Cat 5 cable. Is there something that I (and the satellite company) missed with Vista? Where do I go next?