The cmd.exe is the 32-bit dos emulator (let me call it the more modern; the one most often used). Command.exe is the 16-bit version. Let me call it the old-version. It's apparently for use if you cannot run under cmd.exe.
See the following MS article:
Running Nonnative Applications in Windows 2000 Professional (applies to XP as well)
As RC has mentioned, XP will not allow dos programs that need to run in "real mode", nor those that address the hardware directly. Meaning non-friendly, non-standard programming. Other than that, many dos programs can run. From a command prompt and or by setting up a shortcut to the ".com / .exe" and making your settings (for Full screen, memory reqs, etc.). Certainly if they can run in Win2000 they will run in XP.
Go Spurs, Go!
> Hi, Jim.
> There is no DOS at all in WinXP. However, there is an emulation of MS-DOS
> that runs so well that I usually don't notice any difference. As a DOS user
> from at least version 2.11, I'm still quite comfy at the C: prompt and use
> this "DOS" window often.
> Click Start | All Programs | Accessories | Command Prompt. (There are
> quicker ways to get there; I have a shortcut on my Desktop, one in my Quick
> Launch toolbar, and a shortcut key.) This should open the window, which you
> can size to suit yourself with Properties.
> Open the DOS window full-screen and try the DOS program. Every one that
> I've tried works! Because of the different way that WinNT/2K/XP handles
> hardware - through the Hardware Abstraction Layer - DOS programs that try to
> deal directly with hardware often have problems, but most non-game programs
> work just fine. True MS-DOS cannot read an NTFS volume, but the "DOS"
> window has no problem with it.
> There are actually two versions of DOS emulator in WinXP, command.com (50KB)
> and cmd.exe (375KB). I'm not clear about the differences, but I'm pretty
> sure that cmd.exe is the one you want, and the one you get as Command
> R. C. White, CPA
> San Marcos, TX
> > I have a client that needs to run a DOS program on either
> > a Windows 2000 or Windows XP PC. The reason is, that the
> > situation with this particular software is that the
> > Windows version is not reliable, while the DOS version is
> > satisfactory.
> > It is my present understanding that DOS can run in
> > emulation within Windows 2000/XP, or something like that;
> > does anyone know for certain? Yesterday, I was told that
> > the only thing in DOS that can be done on the latest
> > operating systems of Windows 2000/XP is to use the DOS
> > command line; this seems incorrect to me, but I could be
> > wrong.
> > If not, then what would be the best solution regarding
> > running a DOS program on either of these most recent
> > operating systems?
> > The possibilities that I have reasoned thus far are:
> > 1 - Full restoration of the PC and partitioning of the
> > drive in the set-up of the system from within Windows
> > itself.
> > 2 - Acquiring Partition Magic from PowerQuest, and
> > partitioning the drive on the fly.
> > 3 - Installing an additional drive with either Windows 95
> > or Windows 98, and running the DOS program from that drive.
> > It seems that using an additional drive would be a
> > superior solution than to partitioning using either of the
> > two previous options, but I do not understand just how
> > this would work and whether it is the best solution.
> > Specifically, would this become an either or situation of
> > having only one of the drives in use as in a dual-boot
> > scenario, or could the PC be running programs on the
> > primary Windows 2000/XP drive and the secondary DOS
> > program using Windows 95/98 concurrently?
> > I hope that I have been reasonably clear here, and hope
> > that someone can put forward a best practice solution,
> > either of these options, or other possibilities. I intend
> > to post this questioning on several newsgroups here, as I
> > am uncertain as to which is the best newsgroup for this
> > inquiry.
> > - thank you -