Administrator VS Limited User
At the moment, I do the same thing on my computer which is to have an administrator account that is needed to install new programs and troubleshooting and a normal user account for playing games and browsing. To have the normal user account for daily tasks will probably save you a lot of troubles. Spamware, adware, malware and viruses are known to install themselves without your knowledge and most probably, you will be warned or the installation will be cancelled automatically as normal user accounts are not allowed to install programs. Sadly though, there are still some exceptions.
Just recently, my computer was affected with Win32.Backdoor-DNM when I was using the normal user account. I got no warning or User Account Control message and it was like activated itself after a reboot. Glad to say that I have successfully removed it and my computer should be free of threats.
The Bad Egg: Win32.Backdoor-DNM
Unfortunately, my computer got infected with Win32.Backdoor-DNM. I was busy googling for solutions and I had completely forgotten to make a screenshot out of it. Picture attached is a screenshot from Windows XP and it is quite similar except Vista is showing Protect instead of Enable Protection. Well, it was a simple Windows Firewall protection window saying that it could not delete the worm successfully. I could either close it or click on the Protect button. If the Protect button were clicked, I will be directed to an anti-spyware software download page. I would not want to install the recommended anti-spyware solution as I was worried that it might be just another spam or spyware.
