Signing up for Google Adwords and Microsoft Adcenter with a CREDIT?

I have a credit from my web host, but these sites want me to put in my credit card number. DOES THAT MEAN THAT IF THE $25 STARTING BALANCE RUNS OUT, THAT I CAN GO INTO THE NEGATIVE? Will it keep charging me?

oh yeah, you need to be really careful when running ads campaigns. i would recommend using an adward verification card instead of using your own credit card, it is way safer.
if you need any recommendation on …