What router model? Firmware version?
Wireless network adapter model? Driver version?
What operating system?

Run Windows Update.
Download and install latest router firmware.
Download and install latest wireless adapter drivers.

Any interference near router or wireless network adapter:
2.4GHz phones
thick walls
microwave devices
any ancient appliances/electronics in the kitchen (RF interference)
bodies of water very close to router or adapter (people, fish tanks, etc.)

10-15 feet for a typical wireless-b/g router with no obstructions or interference should give you a strong/excellent signal. See if you can discover the interfering device with your wireless detection utility or download NET STUMBLER (http://www.netstumbler.com/downloads/). Walk around with your notebook to find the dead spots. When you find one, look to see what is very near your notebook/wireless adapter. What items are directly between (line of sight) your notebook/wireless adapter and your router?