The simple expressions appropriate to study the transmission limitations of WDM systems with dispersion compensated links using inline optical amplifiers imposed by fiber nonlinearities are derived. Two important nonlinear effects, four-wave mixing (FWM) and stimulated Raman scattering (SRS) in the presence of amplifier spontaneous emission (ASE) noise are taken into consideration. The maximum possible transmission distance is discussed in terms of various system parameters such as wavelength spacing, number of channels, total bandwidth, etc. Optimum channel spacing to maximize the transmission distance is found as a compromise between conflicting requirements imposed by FWM and SRS in the presence of ASE noise. Different dispersion compensation configurations (CF+DCF, NZDSF-+CF, NZDSF ++NZDSF-) are discussed in order to find the best one that gives the maximum transmission distance. The optimum channel spacing as a function of number of channels for different dispersion compensation configurations is shown for the first time. The optimum transmission distance, that is the number of amplifier spans, versus the number of channels is also shown.