In 2002, I plan to rollover funds from a SIMPLE IRA into a regular IRA and then covert to a Roth. By that time I will have completed paying taxes on my first Roth conversion that took advantage of the 4-year spread. I project that if I covert all of my funds originating from my SIMPLE IRA in one year, I will be exposed to a higher tax bracket. Is it permissible to make the required rollover of all my SIMPLE IRA funds into a regular IRA at one time, and then make a series of partial Roth conversions that permit me to stay in the lower tax bracket over the following 2-3 year period?

Yes you can. You will need to meet the income requirements to qualify each year. Of course, tax law changes may enhance or hurt your plans.