This post is just so I can paste a URL instead of the same block of text again and again in the forums :)
There's 2 purposes to finding the log files during/after a failed install:
The quick version of the "rules" for finding the right log files:
Using my dev machine's explorer, here's a screen shot of the files from my test machine from an install I did Wednesday morning:
Things to notice:
One last bonus tip: if you have a problem during install (for instance, you get a dialog that pops up saying some operation failed and would you like to abort/retry/cancel), that's the point in time you'll want to go look at the log files.
Why is that? Because once you say Cancel and it starts to go through the "we're failing setup" process, there's lots of attempted rollback operations to undo everything that had been done successfully during the install. Because of this, it's easier to look at the log files when the last thing in the log file is the failure that happened rather than having to scan up past all the rollback operations. The relevant data is in there either way, just a little easier to tell what blew up the moment after it happens. :)