I know these are hard to find so I thought I would post them for you all. The driver for the Cisco Aironet 802.11a/b/g CardBus Wireless LAN Client Adapter (CB21AG) for Windows 7 doesn't work with the Cisco Aironet Site Survey Utility, so we need these older drivers from Atheros to get it working. The drivers are attached to this post. Download the drivers and follow these steps:
1) Uninstall the current driver downloaded by Windows update by going into Device Manager, locating the device, right-click and Uninstall.
2) Turn off all internet connections.
3) Remove the card.
4) Plug the card back in. Automatic driver install will fail so choose to browse for the driver.
5) Select the drivers you downloaded from this post.
6) Once driver is installed, launch the Cisco Aironet Site Survey Utility and it will be working!
This solution is credited to user Bobby4Hire who posted this link originally on his website: