You have to be careful with grain with HDR's, 200 ISO might be to high, you're better off with 100 or even 50, and you're right the tripod would be a good bet....slows things down.
High Dynamic Range, it's quite popular at the moment......it's a blending of three/five or even seven exposures to make a final image that has a full tonal range, I make five, 0 -2, -4 +2 +4 and use photomatix pro
You have to be careful though, cos it can end up looking ghastly.