Virtual Wi-Fi was going to be a Windows 7 feature that would turn your PC into a Wi-Fi access-point so devices could share a connection without needing special software. It didn’t make it into the final cut on the OS, but this free app finishes the work that Microsoft abandoned.
Some of the code that Microsoft Research used to virtualize one Wi-Fi card as several adapters still made its way into Windows 7, allowing Connectify to complete the job.
The result is a shared connection that is different than the usual “ad hoc” network connection, because it shows up as a real access point and also reverts to default settings each time you restart. It allows you to join a Wi-Fi network and run the Connectify hotspot on the same Wi-Fi card. Plus traffic can be encrypted using WPA-2 Personal (AES).