Step 4Whatcha Do on the 360 side
iImage Information

Now that your PC is configuratified, go to the System blade and select Network Settings, and select open "Test Xbox LIVE Connection". It will run a test on the cable connection, I.P. addresses, and the like. When it gets to the Xbox LIVE test, it will ask you to download updates if it's successful. Go find something else to do (not on your 360 or online on your PC) while they download.
If all goes well, you should be able to make your profile LIVE-enabled. I can't remember how I did it, but I'm sure you'll figure it out (or post how to in a comment for me to splice in).
well at least mine dont