I would definitely not
use a "DOS," free or otherwise. DOS was never meant to be secure, and cannot be secured.
Be sure that you also get the distribution media
for FreeDOS so that you can readily reinstall it. Then, use Linux.
It is a relatively simple matter, actually, to install Linux on the machine as its primary OS. Then, if you want to fiddle-around with DOS or anything else, you can install VirtualBox
, which is a very good (and also, free) virtual-machine system sponsored by Oracle. (Yeah, the database people ...)
Set up a virtual
machine, and run FreeDOS on that
... "inside of Linux," as it were.
you can sit back and be amazed
at just what that "little, old" laptop can actually do
. A Linux distribution is a full-featured operating system that can
be made secure. ("DOS" can never be!)
VirtualBox is an excellent way to run "guest" operating systems of any sort.
I took a small computer that was shipped with Windows-95 (and which ran that quite sluggishly ...),
put an optimized Linux onto it, and ... whoosh! It was as if I had a brand-new machine: an efficient
one. I used it for years, until "Old Dobbin" finally croaked.
(I still have the disk drive.)