I think they are memory dumps of the kernel or whole memory (depending on what's configured), so they are binary data. Since I reinstalled the Windows partition a while ago, I had zero crashes on that Windows (
knock on wood), so I have no dump files to look at.
I always used this tool here to diagnose Windows BSODs:
http://www.nirsoft.net/utils/blue_screen_view.html
I'd guess you could run it through WINE. You could also let your brother run the tool himself and take screenshots and have him send you those instead of the dump files.
What you want is the file names of the kernel modules that were on the stack when the crash occurred. It's the lines highlighted with a colorful background in the lower half of the window. You can then try to deduce what driver that file name belongs to and see if there's something to update or settings to tweak.
For this tool, you want to configure Windows for "mini-dump" instead of full dump or whatever other options there are. It can't get anything extra out of a full memory dump.