I also have this exact same -209 error, reading online there is TONS of people with this problem. I have even directly connected my xbox to a brand new vista machine. I still haven't gotten it to work, but to help others here is a list of things to try.
If your vista machine has Windows Live OneCare installed, UNINSTALL it. Disabling it will not work, get rid of it.
If you have windows firewall on do not just disable it, make sure to uncheck it for the LAN connection, if you disable it sometimes it can block connections.
Make sure in your network and sharing center that your Network is a 'Private' network and not 'Public'
In services (Start->Run 'services.msc') make sure that Network List, UPNP and SDDP Discovery services are started.
If you have any anti virus or firewall 3rd party apps make sure to disable or stop them from blocking traffic.
When you have previously connected a vista machine to an extender a certificate is created, to clear it do the following:
Select Start -> Run "mmc"
Select File -> Add/Remove Snap-in
Add the "Certificates" snap-in
On the popup choose "Computer account" and hit next
Leave "Local computer" selected and hit finish
Select "OK" on the "Add or Remove Snap-ins" dialog
Click Console Root, Certificates, Personal, Certificates from the directory tree on the left.
Delete Microsoft Windows Media Center Extender Host certificate.
shut the pc down,
turn on xbox 360 and goto system blade, and select computers.
Disconnect from any computers/media center computers.
Still under the system blade go into memory and delete XBOX 360 Dashboard (I found my under the games menu oddly)
You can also try without using the xbox hard drive.
I have tryed all of this, and it still does not work for me even directly connected. I have a static IP, but it is via the DHCP server. (DHCP Staticly assigns by MAC addy)
If anyone has other ideas to try feel free to list them im stumpd, ive posted on the offical xbox forums and the are just as lost. In fact no one seems to have resolved this issue completly, the cert issues fixes some peoples problems.
This post has been edited by bawitdaba: Mar 4 2007, 11:48 PM