I got a new desktop today (A Dell with Windows 7) and i had poor connection in my room, so i moved it into the living room where my router is and now its sitting 5 feet away from it and i still get a poor connection.
Is the internet speed poor? Or is the WiFi signal strength being indicated as low?
If it's the former, try connecting to the router with an Ethernet cable, disable WiFi (temporarily to ensure all traffic is going through the cable), and test again. It's very possible that it's not a WiFi issue, rather other people using the Internet as well off that router or an ISP issue.