Should ITU-R BT .601-4 be turned on when resizing?
 

I'm using FitCD to resize some 640X480 Divx movies and add borders around it (2 blocks of TV-overscan) for KDVD. I'm in the USA(NTSC). Should the ITU-R BT .601-4 be turned on? I usually turn it on because it gives equal-sized borders all around the video even though the aspect ratio error is higher than if it were turned off.

As Dvix encodings use a 1:1 PC quadra pixel architecture you Do NOT activate "ITU-R BT .601-4" as this stands for example for 720x576 DVD sources.
But FitCD (and maybe moviestacker too) do recognise that when importing the source, so you don't have to worry about that ... normally.