The Firewall service in my installation of XP is purposefully disabled, and my gateway doesn't block any outgoing ports of any kind either. <i>So far as I know</i> Comcast isn't blocking any ports or services either; note the qualifier there. I have not been able to confirm <i>or</i> deny (e.g., can't find any independent reports) that Comcast is using Sandvine or other technology to specifically block Gnutella traffic (bittorrent is working fine).

I'll note here that some hosts Phex attempts to connect to, rather than timing out, come back as explicitly refusing the connection.