After you do an upgrade, you'll see the progress bar say "optimizing". That means it's doing the prebinding, whatever the heck that is. Prebinding can also be done manually using shareware or the Terminal.
Some people have suggested that before installing an update, do a backup then repair permissions and restart the computer. That clears the way for the update. And disconnect external drives.
Personally, I've never had any trouble installing an update and only one problem where a hundredth's place update caused a printing problem that was resolved a month later with the next update.
And all this maintenance stuff doesn't need to be taken too seriously. I was a fanatic about it with OS 9 and earlier but OS X pretty much takes care of itself. I've hadn't had a crash since I don't know when and the computer usually stays on for weeks at a time(sleeps at night).
macintouch.com always keeps a running report for each update. It's a good idea to check there first to see if there are any problems with the install reported. Apple has discussion boards for every piece of hardware and software and are good places to check, too. Post your problems there; Apple has people checking those boards all the time. Just post a rumor there and see how long it takes to get erased. :-)
arstechnica.com has a Mac board on their forums section that is quite good. Macosxhints.com is another great place to find tips, tricks, hacks. Lots of Terminal stuff, too.
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