NIST DTSA-II, as you may know, is freely available (
http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html)(both executable and source) software for quantitative energy dispersive x-ray spectroscopy. DTSA-II has been available for almost a decade and is currently in use all over the world for quantifying x-ray spectra, simulating x-ray spectra and designing better measurements. Unlike commercial products, you can see inside the black box to better understand how the algorithms work or, if need be, make your own customizations.
The most recent revision, called Jupiter, was posted within the last couple of days. Jupiter adds better low energy performance, zeta-factor quantification of STEM-mode thin film analyses and "standard bundles", an improved mechanism for using complex/similar standards. Check out Dale Newbury and my most recent article in Microscopy & Microanalysis "Measurement of Trace Constituents by Electron-Excited X-Ray Microanalysis with Energy-Dispersive Spectrometry" for an in-depth discussion of using DTSA-II for trace analysis.
I am grateful that John Donovan has kindly volunteered to host a NIST DTSA-II discussion board on his Probe Software User's Forum. It is probably long overdue that there is somewhere that users can discuss the foibles of this software package. I look forward to meeting current and future users through this forum.
If you are a member, please feel free to add your website URL to your forum profile