You should go download DOSbox (http://www.dosbox.com/
It's a DOS emulator that will let you play DOS games, without the problems that Vista gives you. It's a little confusing at first (text only, uses DOS commands), but once you get used to it, it helps a lot.
Install the game (using Vista, it's probably on floppy disks, and if you don't have a floppy drive, you can either install the game on a computer that has a drive, and copy the game directory to a flash drive and put it on your Vista computer, or get an external floppy drive), to a folder on the C: drive (like C:\Games\Doom (or whatever you're playing)), then fire up DOSbox, and type in
mount c C:\Games\Doom
(of course, replace doom with the game directory name, or, if you have more than 1 game you can just mount the C:\Games directory, so you can see all of them at the same time)
Then type in C: in DOSbox, and you'll have the games files, then you just need to run the game by typing in doom.exe (again, replace with the actual game .exe)
If all went well, you should be playing your game.
(You can also hit alt+enter before you launch the game, to get full screen. Just type "exit" at the DOS prompt to get out of DOSbox, or alt-enter again to keep DOSbox up)
Edited by madman6510, 03 April 2009 - 07:27 PM.