buy a phone card. You can get a global one for about $0.15/min.
As far as cell phones. Certain providers can activate your cell phone to work in Europe, but you have to bring your phone in to have another chip installed. Also, its still more expensive than 15cents/min.
I think I read something related to this...it said something like cell phones in Europe run on different frequencies than cell phones in the US...hence the need for a new chip to be installed (see above paragraph).