Hey Tbone. I know what your problem is man.First let me explain something.
Windows is essentially running on dos,so basically the dos prompt is really dos itself.
So what does this mean? You don't need a dos emulator since you are already running on dos.
Now why are your games running slow??
I am positive you are only enlarging your dos box window with the little square shape in the top right corner of the dos box? you know how theres a _ BOX X in the top corner,you are pressing the box to make it bigger.
So the solution?
Open up the dos window.Just a straight command prompt,dont double click the exe of the game,but instead go to start,programs,accessories,then choose COMMAND PROMPT.
once the dos box opens,hold the ALT button,then press the enter button. You will then have a true fullscreen mode of dos. From there navigate to the directory of the game and load the game exe file.
for example
type
cd\gamename
game.exe
then the game will load and run just fine.
hope this helps