Because I am working with a TV and not a computer monitor, I do not have the ability to disable scaling. I imagine there could be a consumer TV out there that might have such a setting but it is probably a high-end device. Actually, the 12 year old 37″ Sharp LCD TV I had *did* have a option to turn this off! Yes, it was a computer-friendly TV!
The Vizio does have zoom modes and I am pretty certain I already have it set to something that supports 4:3. Anything else will just distort the image. I will double check this.