I needed a Wi-Fi tool to help with a site survy for the HSMM-Mesh Nodes and my laptop runs Vista, so Netstumbler would not work. MetaGeek has created a replacement for Netstumbler. Open-source Wi-Fi scanner software, inSSIDer, actually works with Windows Vista, Windows 7, and 64-bit PCs. This is also free software that will work with current generations of Windows operating systems. I really like this software and find it easy to use.
From their site:
What's Unique about inSSIDer?
•Compatible with Windows XP, Vista and 7 (32 and 64-bit)
•Uses the Native Wi-Fi API and your current Wireless network card
•Sort results by Mac Address, SSID, Channel, RSSI and "Time Last Seen"
•Compatible with most GPS devices (NMEA v2.3 and higher)
How can inSSIDer help me?
•Inspect your WLAN and surrounding networks to troubleshoot competing access points
•Track the strength of received signal in dBm over time
•Filter access points in an easy-to-use format
•Highlight access points for areas with high Wi-Fi concentration
•Export Wi-Fi and GPS data to a KML file to view in Google Earth
•Filter through hundreds of scanned access points
Check it out and download here: