David R said:
"Personally I have never found the need for a sandbox because I have a robust backup and recovery strategy."
Which is to predispose failure on the part of your security products or grievous user error/hardware failure,the last two not being security issues.
In that that case,I would ask,why do you feel a need for a real time Anti-Virus?
I use Sandboxie and Returnil Premium with a host of on-demands.,My "Backup Strategy" is my "My Documents" folder 7-Zipped, and burnt to DVD-R,and my Windows XP Pro disk.
Hardly robust,but I have never had to use it.
Yes, you can mis-configure a sandbox,and remove a measure of its protection.
You can do the same with Avast!,or any program that allows user configuration.
As far as infections,via downloaded files,it is a simple matter to force either
the download folder,or Windows Explorer in Sandboxie,and submit the downloaded files to the blacklister of your choice,from within a sandboxed environment.
The default Sandboxie setting are a high degree of protection,a higher degree can be obtained by limiting start-run/Internet access,using the "drop my rights" option etc.
Sandboxie is in some respects like a limited user account,one can can of course choose not to use it,for any number of reasons,you cant say it adds no security.