Hello,
Since getting MJ7, I have been digitizing my entire tape collection (Self-Improvement Stuff). My wife thinks I have gone nuts! But I can get about 10 tapes on a CD (mp3 and wma files)
Anyway, what I have found, is that, if you are recording seminars, using a tape player with a MONO setting in it and encoding set to 96Kbits gives me the best result with the least amount of space used.
The down side to recording tapes is the inherient "motor" noise you get. If I had a better equilizer on my tape player, it probably be better. But, the trade off of getting so much on a disk, is worth the annoyance.
Also, the sound card makes a differents. On one computer, the "motor" noise was bad, on another it was almost non-existant.
I haven't tried to record music cassettes so I can't help you there.
Hope this helps!