Richard_b,
Are you planning on recording for a long period of time? This would be the only reason I would suggest writing to a file during the RecordingCallback routine, as there is alot of overhead in disk I/O and if the writing fails or generates an error for some reason in the callback routine, VB WILL crash! If this is what you are looking to do let me know as I started something similar a while ago and can send it to ya.
.Azoth.