airbuslad,
you might do glance at
Aerowinx' "Precision Simulator 747-400 V1.3" (usually named PS1.3). Although a 747-400 CBT program (actually a full simulator), the very complete FMC simulation should give you some familiarity with the Boeing / Honeywell approach of a FMC and the display of information on the ND. Price is in the EUR/$ 280 range.
PS1.3 was originally designed for MS-DOS but, surprinsingly, still runs on most Windows 98, ME, NT, 2000 and XP systems. There is a directory of stores selling PS1.3 on the company website.
Disclaimer: there are differences between the 744 and the 757, and simplifications of the FMC simulation. Use the official documentation of your airline.
EoD