If you get a DWI in a car that you're not insured in meaning you borrowed the car for the day and you are not anywhere in the cardholders insurance policy will the cardholders insurance get affected?

It depends on the insurance company and the situation. If the vehicle was wrecked or otherwise involved in an accident, then yes. If you just got pulled over, probably not. After Hurricane Katrina, the insurance industry is going to be looking for ANY reason to cut off possible bad accounts. This would be one reason to cut the owners off. For loaning their car to an UN-INSURED DRIVER.