i agree totally with problemchild's posts !

forget your cert courses as they are only as good as the Instructor ( i know I am a Microsoft Certified Trainer)

yes win 95 98 xp etc etc are ful 32 bit OS'es and they contain support for 16 bit for backward compatability but 95 and 98 still require DOS elements to load with in the first place that is why you see dos based commands from batch files on start of these OS'es.

NT4.0, 2000, XP etc are fully self reliant OS'es with no DOS needed for loading etc they use a completely diffferent Memory model and handle hardware completely differently.

to cut it short 3x needs dos to exist before installation, 95 and 98 can install on a clean HDD but uses DOS as a preempt fro loading device drivers etc etc
NT 4, 2000,XP etc all stand independent and load there own low level kernel for memory handling and booting etc when loading !

As for the A+ cert course remember that that is CompTIA and not a Microsfot course