Extending wireless range

Well if you have linksys routers you may want to install dd-wrt to pull this off since your router is going to have to recieve the connection and transmit. I've read of directional antennas claiming 2 miles I bet that your 500 ft is possible although this prolly wont be cheap.

Ok linksys routers typically have broadcom chips and an alternative firmware called dd-wrt (google it) exists to provide extra functionality for free. I suggest this firmware since people claim that it gives them up to 4 times the range and sometimes as much a 10 times for short periods before the router overheats. It also enables you to set up wds with wpa encryption so your mother-in-law can transmit a signal to your router and you can retransmit it off yours (downside is you only recieve half signal from your router since the other half is concentrating on recieving). You may still need directional antennas which I'm not much help on since I've never had to broadcast that far but just find one rated for double the distance with the right connector and you should be ok (I saw one on newegg rated for two miles so it should make it).