Mandy,
For quality the 8400 is better ( the Olympus 7070wz is better too ). Both these cameras have a high quality lens ( the 8400 has Nikon's ED glass ). They also have RAW which gives a level of quality which can't be achieved by little digicams. If I was going to rate them out of 10 -
Nikon 8400 - 9 ( let down be being a bit slow in handling RAW and only single frame with remote control )
Olympus 7070wz - 8.5 ( Auto focus not as good as 8400's Green Macro zone,but faster at handling RAW and Continuous remote control )
Fuji F30/31 - 8 (faster, low noise sensor up to iso 1600, no RAW,non-ED glass )
The Fuji E900 has RAW and filter thread for adapter and is still available so should be a good option for people who want more functions for digiscoping.