Aflac was kind of correct.
In poor lighting with "Auto ISO" active, the camera will use that as part of it's exposure measurement and increase the ISO to a point that the shutter speed will still be somewhat acceptable (there's a limit to what the camera is capable of before it just can't expose an image in low-enough lighting). You shouldn't see blurry photos, but you will see increasingly noisy photos.
If you set ISO to 100, you take that out of the camera's metering measurements and force it to adjust shutter speed and aperture (also known as f-stop and is displayed on the front lens ring as f2.8-6.3, etc, whatever your camera is capable of. The lower the f-stop, the more light gets thru the lens).
For most P&S cameras, it is best to set a fixed ISO, such as you are considering setting at 100, and then utilize the built-in flash to compensate for low light. Using flash will allow the camera to use a faster shutter speed, thus reducing blurry images from hand/camera shake. This is only feasable in close-in situations such as close-range people shots, party pictures, etc, as the built in flash is not powerful enough to light up an entire outdoor scene, for example.
You will find times where you may need to increase the ISO since it may mean getting a noisier picture versus getting no picture at all.