Call me a geek, but I like to play old dos games (like stelcon3, jazz jackrabbit, epic pinball, etc). I've tried a couple of solutions to get them to work.
First is FreeDos running under either VMWare or Virtual PC. FreeDos is a great program, and I'm sure it works well for many people, but it does not work well for playing the old games.
Running under either virtualization platform, it frequently gives weird errors with Emm386 (vmware 4.5 and ems just don't get along well together I guess--if you load Emm386 with the NOEMS option, it'll work). And even with SlowDown running, the games are just unplayable--the graphics simply aren't smooth enough, and the emulated video card doesn't work with a lot of games.
So the alternative is DosBox. Dosbox seems to work very well! It's specifically designed to run old games so a lot of the features you need are built in, like the emulation of old video cards and such.
If you need networking or compilers or other tools, use FreeDos, but if you just want to play the games, DosBox is the way to go.