According to the how-to here http://www.vcdhelp.com/tmpgenc.htm , it says that:

Select Video-CD
NTSC if the video source is 29,97
NTSC Film if the video source is 23.976
PAL if the video source is 25 FPS.
So if my nAVI is 20fps, do i use NTSC film since it is closest to 20fps?

In any case, how do i change the setting to get the best quality MPEG file from nAVI? (For eg, a nAVI 352x288, 54kbps, 24bit video sample size, 20fps, 40kbps bitrate, Mpeg layer 3) Cos i realise that the sound and pic quality reduces after the conversion.

Thanks in advance