Woo Hoo my old DOS games work!!! With sound even!!! How do they do that?

I do have one problem though. I start the games under DOSBox and they run fine in windowed mode, and in full screen mode (I've tried Master of Magic and Colonization so far) but they are a bit slow. However when I use Task manager to increase cycles the keyboard no longer works. Mainly the arrow keys for movement but also any letter keys the game needs. I'm using XP with a standard Microsoft keyboard.