Free internet, share your existing one using wifi

Some people want to reduce internet cost by sharing existing internet connection.
Yes its possible. And there is a good software for the Windows. And its works excellent in Windows 7. Also works on Windows XP, Vista and so on. Though I have not tested, I cannot assure you the performance on these except the Windows 7. And sharing is free. You can also protect your network using password.
Download Link for Connectify