For the most part - default Windows XP Firewall blocks all incoming ports.
You have to allow most ports through exceptions.
Windows XP Firewall does nothing for outgoing connections.
Inbound or outbound?? The Windows Firewall blocks all and then you define
the allowed exceptions for inbound traffic. If you are using XP Pro you can
use ipsec policy to block inbound or outbound with firewall like rules. The
link below gives the basics of an ipsec filtering policy. --- Steve
