  We describe the effect that new atomic calculations, including
fully-relativistic R-matrix calculations of collisional excitation rates and
level-specific dielectronic and radiative recombination rates, have on line
ratios from the astrophysically significant ion Ne IX. The new excitation rates
systematically change some predicted Ne IX line ratios by 25% at temperatures
at or below the temperature of maximum emissivity (4x10^6 K), while the new
recombination rates lead to systematic changes at higher temperatures. The new
line ratios are shown to agree with observations of Capella and sigma^2 CrB
significantly better than older line ratios, showing that 25-30% accuracy in
atomic rates is inadequate for high-resolution X-ray observations from existing
spectrometers.
