Per my Link Sys wireless router documentation, it's 300 ft indoors & 1500 ft outdoors at 1 Mbps. The closer to the router you are, the faster the speeds are.

I read an article about wi-fi recently & it talked about Starbucks (I think) which offers wi-fi access in some of their stores. There are people living in apartments around at least one of the stores that are getting internet access for free by using their own wi-fi compatible lap tops & Starbucks internet wireless.
Regards
Bill R-4581