On Windows 7 (or Vista) I use
Privatefirewall goes free! (2009/07/30 18:36)
A great news for all fans of Privatefirewall has been announced by its vendor PWI, Inc. Since Privatefirewall 18.104.22.168 (the latest version at the time of this announcement), the whole product is free of charge, without any limitations. Also, the new version is ready for Windows 7. Other related products of PWI, Inc. including DSA (free product with only a part of the functionality provided by Privatefirewall) have been discontinued.