re: an '04 Lexus RX330: if timing belt breaks will it ruin the engine?

What is your question?

My daughter's timing belt recently broke in her 2003 Saturn Vue - whuch resulted in the pistons destroying the "head" of the engine. Estimates are $3,500 - $4,000 to replace the engine. Is this symptomatic of only a certain type of engine - and, do we need to be concerned that the same thing could happen with a 2004 Lexus RX330 Engine? Further, how often should the timing belt be replaced? How do you know when it is necessary? Thanks!