inSSIDer is a free Wi-Fi network scanner for Windows Vista and Windows XP. Because NetStumbler doesn't work well with Vista and 64-bit XP, we built an open-source Wi-Fi network scanner designed for the current generation of Windows operating systems.
Inspect your Wi-Fi and surrounding networks.
Scan and filter hundreds of nearby access points.
Troubleshoot competing access points and clogged Wi-Fi channels.
Highlight access points for areas with high Wi-Fi concentration.
Track the strength of received signals in dBm over time.
Sort results by MAC Address, SSID, Channel, RSSI, Time Last Seen.
Export Wi-Fi and GPS data to a KML file in Google Earth.
Main Features -
Uses your current wireless card and connection software;
Works with Windows XP, Vista, and 7 (32 and 64 bit); Compatible with most GPS devices (NMEA v2.3 +).