I had posted earlier about how I was able to crash my machine consistently by running iMovie playback, Handbrake transcode, and open Photo Booth and/or FaceTime for realtime isight video. Never tested to see what the minimum it'd take to freeze the machine, but running a handful of these at the same time would do it, every time.
I just ran the 10.6.7 update for MacBook Pros (or whatever they called it) and I am currently running a queue of Handbrake transcodes, playback in iMovie, watching a HD trailer in Quicktime player and another in iTunes, Photo Booth and FaceTime are open, a movie on Vimeo playing in Safari... (think that's it)... and...
NO CRASH! Been running these for about 6-8 minutes now. Before I would get a freeze in a minute or two of the fans blowing, consistently.
So far so good... Will try the Terminal "yes" test which I had never done before. Not sure what else to check for, but I think I feel confident now in installing my aftermarket HD and RAM when that shows up today, and installing my software. Previously I was planning on taking it back to Apple later today or tomorrow.
Still going, no freeze... 🙂