Nowadays personal computers [PCs) have sufficiently high speed of calculation and large memory and can be used for precise modeling and implementation of the fundamental parameter methods in the x-ray fluorescence (XRF) analysis. Because of its low price the PC is generally a standard component of energy-dispersive and wavelength-dispersive x-ray fluorescence analyzers, and allows not only automation and control of the whole spectrometer during the scientific experiments or routine analysis, but also complete on-line calculation of concentrations {using sophisticated calibration models), QA/QC monitoring, and archivation of the data. Together with the development of faulti-task operation systems for personal computers the efficiency of their use became higher. A few years ago the main requirement for the software was that it be optimized in order to perform many sophisticated calculations in as short time as possible, and less attention was paid to the interface “computer-user”. Now, with much more powerful new generation PCs, one of the main requirements on the software for XRF analysis is to be “user-friendly”, i.e. not to require special education and extended learning period before using it and to ensure high flexibility of application of the programs.