Undocumented Alien, all valve games use hl2.exe, and they all run from a different folder, which is probably why your firewalls want to re-auth them seperately.
I use Zone Alarm and it will usually tell me when a program wants access to the internet etc, but this doesn't seem to be the case for TF2, it loads to a point then crashes. I get past the 'first' splash screen (with the medic as focal point) then it crashes at the second splash screen.
I'm hoping the launch options will help, or just the new download...
DAM I want to try this out!!!