Although Vista's firewall will ship with both in- and outbound filtering capabilities, the latter will be disabled by default. Corporate users, however, can turn on outbound if they wish.
"Inbound filtering is on by default and outbound filtering for applications is configurable by enterprise administrators through Group Policy," said a Microsoft spokesperson.
Microsoft has been promoting Vista's firewall as better than XP's because it's able to stop both incoming attacks and filter outbound traffic. But with it enabled only for incoming data, the end result is a defense identical to Windows XP SP2, which has an incoming-only firewall that's automatically enabled.
Selective outbound blocking has been offered by other firewall providers, including Symantec and ZoneLabs, for years. The tactic is used to stop unauthorized programs from accessing the Internet, and touted as a way to prevent spyware from transmitting stolen data to criminals, even if the spyware gets past other protection and burrows its way onto a hard drive.