someone has to execute malware, and I'm not one of them.
No. That's not at all true. This is the ignorance I was referring to. Every application you run that interacts in any way with outside data is a potential attack vector, and any exploitable code in those applications can lead to malware being run
without the user doing anything. The fact that you don't seem to realise this just underlines how widespread user ignorance is and how people thinking they know better can be very troublesome -- not just for those people but also anyone who has the misfortune of sharing a computer with them and possibly anyone else on the internet who gets bothered by DDoS, spam, or whatever else this newly infected computer chooses to unleash on the rest of the internet.
This is why limited user accounts are a necessity. This is why every other PC OS has used the multi-user concept for decades and defaults to limited privileges for general usage. Vista is Microsoft finally catching up to where everyone else has been for a long time. They've actually made the right choice with their security model (even if they've botched the implementation a bit in UAC) and for all the things that people might choose to complain about in Vista its multi-user setup is not one of them.
You'll have to excuse me if I consider your determination to spread user data all across your computer to be secondary to everyone else's need not to suffer the consequences of your mistakes.
