I think it's important to pick the appropriate software for the aircraft you wish to fly. Learning to use one type may confuse you if you are training for a different aircraft type. Aerowinx's sim is suitable for 747-400's and possibly 777's. A reasonable FMC simulator for 767's and 757's can be found in the Microsoft Flight simulator (2000/2002) add-on "PIC 767". With both sims, you get a complete aircraft and manuals, not just an FMC.
There are forums for both sims which may help you decide which sim is more suitable. If you already have a computer, it's important to determine whether on not it will run this simulation software.
Regarding books... The FMC "bible" is Bill Bulfer's "Big Boeing FMC Users Guide" (applicable to all Boeings, highly detailed and full of useful tips). However, it is heavy reading and really requires a freeplay simulator such as those mentioned above to help you absorb what you are reading.
Rgds.
Q.