I am planning to capture from different video sources , using Avi_io, huffy ,yuv, marvel g200, athlon 1400.
My question is, is it worth capturing at a resolution high than its source
editing and then re-encoding?
If not could you please tell me what the actual resolutions are for the following formats

Pal tv broadcast (tuner on Marvel)
Pal vhs via composite input
Pal tv broadcast via cable (telewest)
Pal dvd via composite input