OK - I give up. I like UAC (User Account Control) in Vista - well I like the concept. But its implementation utterly sucks and is painful to use. Yes, I know the idea, but the implentatation is overly simplistic - relying as it does on 'authorising' each attempt to elevate priveleges. It just gets folks into the habit of clicking "yes - please go do whatever I just asked you to do" button. Which of course becomes a target of social engineering.
UAC is just not good for my blood pressure. So, thanks to the Windows Vista Build 5365 Tweak Guide, UAC is gone - and Vista is better. Bliss - or nearly. This guide to 5365 is not bad, although in step 3 to disable UAC, you have to click the Launch button (not the run button). This page has some other useful tweaks I'll explore in due course.