Belly heat is important, although I don't think a heat pad is the only way to do it. I use a red heat lamp, the one zoomed makes, and the reptibark substrate is actually pretty warm on the warm side of the tank. I used a heat pad in the winter when room temps dropped, but otherwise I have used a heat lamp successfully with my '04 hatchling.

I think its really a matter of personal preference. I've seen both used with good results.