  To underscore the value of high spectral resolution for the study of low-z
QSO absorption lines, we briefly present Space Telescope Imaging Spectrograph
echelle data that demonstrate how increased resolution leads to dramatic
improvement in line measurements. We show that even R = lambda/Delta lambda =
20,000 is insufficient for some measurements. The higher the resolution the
better, but R ~ 50,000 is adequate for many outstanding questions about the IGM
and the ISM of galaxies that can be probed using QSO absorption lines.
