Celeron D. 2.93GHz, 256K cache 533Mz fsb, pc2700 DDR standard.
Duron. 1.8GHz 64K cache, 266MHz fsb, pc2100 DDR standard.
I'd go with the Celeron.
EDIT: The Celeron also runs cooler than the Duron and has a much better stock hs/f. The CPU itself is also a lot more durable.