OT: new computer for eldest daughter

[geoschmo]

Assuming you already have a router for your exsisting LAN, like you would get with a DSL or cable hookup, and assuming the router has an open network jack available, what you are looking for is what's called a wireless access point. In effect it's how you described it, the access point jacks up to the LAN via standard network patch cord, and communicates directly with the wireless NIC card in your laptop. The limit is gonna be about 1000' feet under ideal conditions, less in the real world. Going through walls, etc, cuts down on the distance the signal can travel. Unless you have a neighbors house closer then that you shouldn't have any concern with squatters, but as Narrew says there are ways to eliminate any possibility of that. The software to do that will most likely come with the access point.

Geoschmo