Windows 7: Network adapter problem

Whenever I go downstairs with my laptop near my router I get a strong connection to the internet (without ethernet cable), but when I go to the room upstairs it is a 4 bar connection but is always unable to connect.. any ideas to fix?

Interference? Try changing the channel the router uses for wireless. Also try moving the router location.

Are there other wireless devices in the upstairs room? If so, try disconnecting them and see what happens.

Edit: You could also try replacing the routers antenna (if it has one) with one that is moveable and amplified, something like this: D-Link - ANT24-0700 - 7dBi Omni-Directional Indoor Antenna at TigerDirect.com