Yeah, if you don't make xsession non-executable and just add gdm X will not run, I also found that out a while back, I ended up with an X crashing endless loop.

Also something I've figured out the hard way, it's a real good idea to leave things in place (especially system scripts) and just make them non-executable, then if you are forced to go back to an initial setup it is easy to undo things, but if you delete a file (as I've done, too many times) and you can't get it from another machine it's time for a reinstall, been there done that, way too many times. Actually knoppix is really cool in this way because you just have to boot up the cd and copy the necessary file over to the install and it's back to where it was.

rock