When using the 1964, beware of the following:

Even if the game runs well and for some reason you just happened to lose you save files
(you know the times you save with data in game) chances are that you get them back.
I lost mine so many months before making this thread and there they are. Ito's a miracle!!

Nevertheless, the re´s something you have to be EXTRA care full about... don't use F2 and F4 
to save and load state respectively, this will probably mess your mega man experience like no other thing possibly can.
I JUST DID THAT and it stop running. The screen turned black and I couldn't save or load the game. Fine I said...
Next thing I know I reset the game and once I got to the main many window, I clicked to see my save files (the in game ones)
and they were gone!!!

Another thing... chances are that if you choose to begin your mega man adventure using the 1964 option,
you wont be able to stop the game ( at least I cant). That's why I got so surprised when I tried to save using F2 and 
suddenly the game stopped. 

Well, one mans fall is another ones gain I guess... use my experience as a heads up. 

PS : This game ROCKS!!!