Home Network :: How To Establish Wireless Connection Between Two Houses

I need to get the internet from my uncle and aunt's house to my grandma's house next door. I don't know exact feet or anything like that yet but I will get it measured off. My grandma's kids got her a laptop for Christmas but she doesn't have the internet or would be wanting to spend money on it a month since she already says she will not be able to use the computer, but I said we would just somehow get the internet from next door. I don't know off the top of my head but my aunts computer is an older Dell, early P4 computer with xp on it. It's slow but it does work so that is the computer. The router is some sort of D-link with one antenna on it and I'm pretty sure it's probably a G-router(2.4ghz) and not a N-router, but can get that info later too! They currently use Time Warner Cable Roadrunner Turbo for their internet. Both places are well built brick houses and at least 200-300 feet apart. I checked yesterday and the computer was able to pick up the signal in my grandma's house on the end that was closest to my aunts house. It was showing 2 bars but it wasn't extremely fast and that room had a bigger window in it probably allowing some of the signal in? If you moved from that point of the house though and tried to go to the other end, the signal was lost. The router in my aunt's house is one room away from the end of the house that is closest to my grandma's so it could be moved closer but I don't think that will fix the signal enough to do what I need it to do.