Not too keep beating a dead horse (but here is one more whack), you can read this right on the Visa website (see below). I will concede that with a debit card they would be stealing from you're checking acct and not from your credit account, but you do have the same protections against fraud.
"Gain peace of mind with Visa's extra security protections.
When you sign for your purchases, your money comes directly from your checking account, but you also get security protections that help prevent, detect and resolve fraud, including:
Visa's Zero Liability Policy*, which protects you from unauthorized charges. Any funds taken from your account due to fraudulent use will be returned to you.
Continuous fraud monitoring to detect and prevent suspicious activity on your debit card
Access to Identity Theft Assistance to help you recover your identity and prevent further problems
A 3-digit security code to verify your identity for Internet and phone purchases.
Here's how to sign for your purchases:
Swipe and Sign: Use your Visa Debit card, tell the cashier you want to sign for your purchase and sign the receipt.
OR
At a PIN pad: Swipe your card, select CREDIT on the keypad and sign the receipt.
You'll receive these same security protections when you use your Visa Debit card for online, phone and mail orders or for purchases at merchants that do not require a signature."
From Visa Website