Aaron Margosis has this radical tool called MakeMeAdmin ... read on for my experience on adhering to the principle of least privilege.
Basically, I've been looking to make the switch to securing my home system for quite a while. Rewind to about six months ago. I was running Windows XP, but there was only one account on the machine, this account was shared by me, my wife, and my daughter. Needless to say, this was a big mess because my developer tools were interwoven with my wife's shortcut URL to the bank's website ... in short, there was no organization. On top of that, I was using internet explorer and outlook express, two products that don't have the most stellar security track record (though thankfully I've never been compromised via those apps before). But the most significant thing in my opinion was the fact that I was running as administrator.
Now, I've since been enlightened that you shouldn't do that (run as administrator), but I was also told that things wouldn't work right ... applications would basically demand to run as administrator. So I never got around to making the switch.
About a month or so ago, I got a chance to upgrade the computer ... I reinstalled windows and started fresh. Now, everyone has their own account, but they were still running as administrator so that my wife could install stuff if she needed to. However, last night, I finally made the switch based on Aaron's advice ... that weblog has some pretty darn good advice. That, coupled with the fact that I'm only running the Visual Studio 2005 beta at home (which so far has not given me any problems running with least privilege) made it an easy transition. All I had to do was a small bit of training with my wife to let her know that if she had to install anything, she would have to switch to the admin user to do so.
Admittedly, I have not run any games yet ... I suspect I will have issues there, but hey, I've got my trusty PS2 by my side so I'm not entirely worried. I will post more if any significant issues arise.