A lot will depend on the quality of the remote PC or laptop. I have a Gericom laptop with integral WiFi which comunicates with my Belkin router which is in the centre of my house through two 18 inch thick granite walls out into my garden quite happily with about 70-80% signal level. A friend brought round a Dell laptop with a plug in WiFi card and it was only managing about 15-20% signal strength with a corresponding reduction in transmission speed.