8.10 and Vista Connection Problem

I built a computer for a friend and I put Ubuntu on it. I'm trying to update it by using his Laptop as a gateway for the interent. You know, use the Laptop to receive the internet and LAN it to get the connection. I've done it a lot of times with my computer and my cousin's laptop, but my cousin has XP; my friend uses Vista. And we can't get a connection between the two at all. It tries to connect, but after a while, it give up and says there's no connection. I was wondering if this was common and if it was an easy fix. Any help will be appreciated. Thanks.