A set of new Intel WiFi drivers, v. 13.0.0.107 adds driver-level support native Virtual WiFi in Windows 7.
32-bit: http://downloadcenter.intel.com/Detail_Des...62&lang=eng
64-bit: http://downloadcenter.intel.com/Detail_Des...62&lang=eng

After downloading and installing the drivers (32-bit here, 64-bit here), assuming your WiFi chipset supports the functionality (which I can verify the 5300 can but 3945 cannot), a new “Wireless Network Connection” with the adapter name “Microsoft Virtual WiFi Miniport” will automatically appear in your network connections.

Article @ i started something

How it works:
http://www.istartedsomething.com/20090516/...osoft-research/

Connectify provides a nice GUI for this (beta at this time)
http://www.connectify.me/