Files for emulators:
.Msa - Yes, can be written to disks
.st - Yes, can be written to disks
You'll need a program called makedisk.exe
Boot into dos mode, format your disks to 720kb using:
(where a: is your floppy disk drive)
This will format your disks. However, you'll need either 720kb disks, *or* 1.44mb disks with a piece of tape over the hole on the disk (the hole that isn't used for disk protection). Note that 1.44mb disks are *not* advised for use, but ok if you're in a bind.
Now that you have some nice, blank 720kb disks, it's time to use makedisk.
Using makedisk is pretty simple. The easiest way to write to disks from the disk images, is to place both makedisk.exe and the disk images in the same directory, then type:
makedisk /write diskimagename /auto
makedisk /write auto300.st /auto
makedisk /write aaargh.msa /auto
Just follow the prompts, and away it goes.
Hope this is what you wanted. Note that when I say to boot to dos, I don't mean to simply open an ms dos window. If you are running windows at the time, windows will interfere with makedisk and kill your floppy disk.
Anyway, hope things work out.