You're correct. I was just try to imply that the 10.5.7 update isn't a catastrophe of an update that will overheat all Macs. I was trying to make the case that this incident appears to be isolated to a few individuals.
To the OP, if you are really concerned, you can one of three things:
1. Don't update and stick with 10.5.6.
2. Back up everything you have, update and monitor your machine. If all goes well, you're fine. If not, at least you have a backup in case a drastic solution is in order (such as reinstalling OS X).
3. Stick with 10.5.6 for now and wait for 10.5.8, which I hear is being tested now.