Phew...depends on environment.
If you believe the box one of my wireless adapters came in the range varies from 1605ft outdoors (but at minimum performance) to 835ft outdoors at max bandwidth. So don't put your router next to the window.
Indoors is a very different story the box claims a maximum of 500ft at minimum performance and 175ft for max performance.
However I don't believe the box -- rather the rule of thumb that says 50ft or 3 walls and that's with a big hit on performance.