I am very particular about the sound quality of my Captivate presentations. I currently use an older Plantronics DSP headset, which records excellent quality narration ONLY if my MacBook Pro is running on battery, which really limits the amount of audio I can record. With the MBP connected to a power supply the audio is unusable. I have also tried using the built in microphone on the MBP but it sounds like it's in a tin can. A friend lent me a new Pantronics headset which isn't effected by the power supply of the MBP but it picks up so much other noise that even a quiet office sounds like a trainstation.
This problem existed in earlier versions of Captivate running on XP on the MBP and hasn't changed at all since switching to Captivate 5 for Mac.