Before revision: [{\em  ] Experiments are run with implicit Runge-Kutta stages up to s=7, and it is found that the new preconditioner outperforms the others, with the improvement becoming more pronounced as spatial discretization is refined and as temporal order is increased.
After revision: [{\em , 27 (2006), pp. 109-123] Experiments are run with implicit Runge-Kutta stages up to s=7, and it is found that the new preconditioner outperforms the others, with the improvement becoming more pronounced as spatial discretization is refined and as temporal order is increased.