What's the Cheapest Way Use my Cell Phone in Israel?

Hello.... I'm here in the U.S. and I'm traveling to Israel in November. I checked into cell phone rates or what I can do to change my plan so I can use my cell phone while there, and rates are astronomical (I have AT&T, formerly Cingular)! Someone once told me that when I get to Israel, I should just purchase a prepaid sim card there that I can insert into my existing cell phone, and the rates are much cheaper. Is this true? Can it be that easy? If so, where can I look online for information on that, and what are rates like? Thanks!