All I can say is "Wow!"
It is far worse than I had imagined. The "Windows Experience" for Vista was obviously designed by running XP through a salad shooter and drawing new icons for whatever came out wherever it landed, and then "fixing" everything that still worked right.
If you get "access denied" or "you need permission to perform this" messages the only solution is to reformat the hard disk and start over. The file security features simply don't work. You can take ownership, propagating it down the tree, then give yourself full rights to everything and it goes through the motions but doesn't actually change anything. You still have no access and no permission. It doesn't matter if you have that "User Access Control" thing turned on or off either.
Fortunately, reformatting was not a problem because the client's daughter had already tried to install Vista and it wiped all her precious documents, music and pictures completely, creating inaccessable directories with nothing in them. All that was left was some birthday party pictures that had been put in a non-Windows folder.
Yes, I examined the disk thoroughly on a Linux system with NTFS-3g (and copied off that one surviving folder).
If an install fails and you have to install over, you're stuck with a 7 or 8 gig folder structure from the previous install that you just can't get rid of. If you turn your back on the install, instead of coming up on the hard disk when it restarts, it comes up on the CD and restarts the install. You figure the install failed, go through again and now you have another 8-gig folder you can't get rid of.
Typically, Defrag runs silently with no "details" button. It doesn't show you the condition of the disk before or after or what it's doing or how far along it is. That must be to make it consistent with the error and message pop-ups which provide no interpretable information whatever. Everything is dumbed down to the moron level to hide the fact that it doesn't actually work right.
My researches on the Internet show that others are having similar or even worse experiences and workable solutions to problems are rarely posted - most of the replies are just wild guesses or insults. And over on Groklaw some poor Dutchman has just posted his experiences trying to get Vista to write a CD.
I could go on and on and on but my brain has mercifully deleted most of my Vista experience due to the bad smell.
I'm pretty sure Vista was released in this sorry state because development efforts to make it actually work were just making it worse.